diff --git a/tests/ref/basic.list b/tests/ref/basic.list
index cdc448a8173..f0cfd3c2f42 100644
--- a/tests/ref/basic.list
+++ b/tests/ref/basic.list
@@ -13,17 +13,6 @@ fragment=top != ../html/acid2.html acid2_ref.html
 flaky_cpu == append_style_a.html append_style_b.html
 # `?` and `#` in the name is a test for https://github.com/servo/servo/issues/3340
 
-== iframe/simple_inline_height.html iframe/simple_inline_height_ref.html
-== iframe/simple_inline_max.html iframe/simple_inline_max_ref.html
-== iframe/simple_inline_min.html iframe/simple_inline_min_ref.html
-== iframe/simple_inline_width.html iframe/simple_inline_width_ref.html
-== iframe/simple_inline_width_height.html iframe/simple_inline_width_height_ref.html
-== iframe/simple_inline_width_percentage.html iframe/simple_inline_width_percentage_ref.html
-== iframe/size_attributes.html iframe/size_attributes_ref.html
-prefs:"layout.writing-mode.enabled" == iframe/size_attributes_vertical_writing_mode.html iframe/size_attributes_vertical_writing_mode_ref.html
-== iframe/stacking_context.html iframe/stacking_context_ref.html
-== iframe/stacking_context_position_a.html iframe/stacking_context_position_ref.html
-
 # inline_border_a.html inline_border_b.html
 flaky_cpu == linebreak_simple_a.html linebreak_simple_b.html
 # Fails intermittently (#3636)
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index a0758e89e18..8a152e381bb 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -1687,6 +1687,126 @@
             "url": "/_mozilla/css/iframe/simple_inline_default.html"
           }
         ],
+        "css/iframe/simple_inline_height.html": [
+          {
+            "path": "css/iframe/simple_inline_height.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_height_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_height.html"
+          }
+        ],
+        "css/iframe/simple_inline_max.html": [
+          {
+            "path": "css/iframe/simple_inline_max.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_max_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_max.html"
+          }
+        ],
+        "css/iframe/simple_inline_min.html": [
+          {
+            "path": "css/iframe/simple_inline_min.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_min_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_min.html"
+          }
+        ],
+        "css/iframe/simple_inline_width.html": [
+          {
+            "path": "css/iframe/simple_inline_width.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_width_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_width.html"
+          }
+        ],
+        "css/iframe/simple_inline_width_height.html": [
+          {
+            "path": "css/iframe/simple_inline_width_height.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_width_height_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_width_height.html"
+          }
+        ],
+        "css/iframe/simple_inline_width_percentage.html": [
+          {
+            "path": "css/iframe/simple_inline_width_percentage.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/simple_inline_width_percentage_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/simple_inline_width_percentage.html"
+          }
+        ],
+        "css/iframe/size_attributes.html": [
+          {
+            "path": "css/iframe/size_attributes.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/size_attributes_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/size_attributes.html"
+          }
+        ],
+        "css/iframe/size_attributes_vertical_writing_mode.html": [
+          {
+            "path": "css/iframe/size_attributes_vertical_writing_mode.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/size_attributes_vertical_writing_mode_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/size_attributes_vertical_writing_mode.html"
+          }
+        ],
+        "css/iframe/stacking_context.html": [
+          {
+            "path": "css/iframe/stacking_context.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/stacking_context_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/stacking_context.html"
+          }
+        ],
+        "css/iframe/stacking_context_position_a.html": [
+          {
+            "path": "css/iframe/stacking_context_position_a.html",
+            "references": [
+              [
+                "/_mozilla/css/iframe/stacking_context_position_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/iframe/stacking_context_position_a.html"
+          }
+        ],
         "css/image_rendering_auto_a.html": [
           {
             "path": "css/image_rendering_auto_a.html",
@@ -7254,6 +7374,126 @@
           "url": "/_mozilla/css/iframe/simple_inline_default.html"
         }
       ],
+      "css/iframe/simple_inline_height.html": [
+        {
+          "path": "css/iframe/simple_inline_height.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_height_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_height.html"
+        }
+      ],
+      "css/iframe/simple_inline_max.html": [
+        {
+          "path": "css/iframe/simple_inline_max.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_max_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_max.html"
+        }
+      ],
+      "css/iframe/simple_inline_min.html": [
+        {
+          "path": "css/iframe/simple_inline_min.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_min_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_min.html"
+        }
+      ],
+      "css/iframe/simple_inline_width.html": [
+        {
+          "path": "css/iframe/simple_inline_width.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_width_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_width.html"
+        }
+      ],
+      "css/iframe/simple_inline_width_height.html": [
+        {
+          "path": "css/iframe/simple_inline_width_height.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_width_height_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_width_height.html"
+        }
+      ],
+      "css/iframe/simple_inline_width_percentage.html": [
+        {
+          "path": "css/iframe/simple_inline_width_percentage.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/simple_inline_width_percentage_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/simple_inline_width_percentage.html"
+        }
+      ],
+      "css/iframe/size_attributes.html": [
+        {
+          "path": "css/iframe/size_attributes.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/size_attributes_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/size_attributes.html"
+        }
+      ],
+      "css/iframe/size_attributes_vertical_writing_mode.html": [
+        {
+          "path": "css/iframe/size_attributes_vertical_writing_mode.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/size_attributes_vertical_writing_mode_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/size_attributes_vertical_writing_mode.html"
+        }
+      ],
+      "css/iframe/stacking_context.html": [
+        {
+          "path": "css/iframe/stacking_context.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/stacking_context_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/stacking_context.html"
+        }
+      ],
+      "css/iframe/stacking_context_position_a.html": [
+        {
+          "path": "css/iframe/stacking_context_position_a.html",
+          "references": [
+            [
+              "/_mozilla/css/iframe/stacking_context_position_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/iframe/stacking_context_position_a.html"
+        }
+      ],
       "css/image_rendering_auto_a.html": [
         {
           "path": "css/image_rendering_auto_a.html",
diff --git a/tests/wpt/mozilla/meta/css/iframe/size_attributes_vertical_writing_mode.html.ini b/tests/wpt/mozilla/meta/css/iframe/size_attributes_vertical_writing_mode.html.ini
new file mode 100644
index 00000000000..6b6f0d62fe0
--- /dev/null
+++ b/tests/wpt/mozilla/meta/css/iframe/size_attributes_vertical_writing_mode.html.ini
@@ -0,0 +1,3 @@
+prefs: [layout.writing-mode.enabled:true]
+[viewport_meta.html]
+  type: reftest
diff --git a/tests/ref/iframe/simple_inline_height.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_height.html
similarity index 83%
rename from tests/ref/iframe/simple_inline_height.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_height.html
index be28febf1ef..22c0ef4c393 100644
--- a/tests/ref/iframe/simple_inline_height.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_height.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_height_ref.html>
  <body>
    <div style="margin-top: 20px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_height_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_height_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_height_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_height_ref.html
diff --git a/tests/ref/iframe/simple_inline_max.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_max.html
similarity index 84%
rename from tests/ref/iframe/simple_inline_max.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_max.html
index fb1a075247a..56dbd15abbe 100644
--- a/tests/ref/iframe/simple_inline_max.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_max.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_max_ref.html>
  <body>
    <div style="margin-top: 20px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_max_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_max_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_max_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_max_ref.html
diff --git a/tests/ref/iframe/simple_inline_min.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_min.html
similarity index 84%
rename from tests/ref/iframe/simple_inline_min.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_min.html
index e8466c5d570..601fa3a3192 100644
--- a/tests/ref/iframe/simple_inline_min.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_min.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_min_ref.html>
  <body>
    <div style="margin-top: 20px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_min_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_min_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_min_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_min_ref.html
diff --git a/tests/ref/iframe/simple_inline_width.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width.html
similarity index 83%
rename from tests/ref/iframe/simple_inline_width.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width.html
index 3020f65ca52..b6d3ca249d0 100644
--- a/tests/ref/iframe/simple_inline_width.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_width_ref.html>
  <body>
    <div style="margin-top: 20px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_width_height.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_height.html
similarity index 82%
rename from tests/ref/iframe/simple_inline_width_height.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width_height.html
index 1c419a30c1d..12c30d30598 100644
--- a/tests/ref/iframe/simple_inline_width_height.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_height.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_width_height_ref.html>
  <body>
    <div style="margin-top: 20px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_width_height_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_height_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_width_height_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width_height_ref.html
diff --git a/tests/ref/iframe/simple_inline_width_percentage.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_percentage.html
similarity index 81%
rename from tests/ref/iframe/simple_inline_width_percentage.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width_percentage.html
index 29b55c2b683..20e2d7aeff0 100644
--- a/tests/ref/iframe/simple_inline_width_percentage.html
+++ b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_percentage.html
@@ -1,4 +1,5 @@
 <html>
+<link rel=match href=simple_inline_width_percentage_ref.html>
  <body>
    <div style="margin-top: 20px; width: 400px;">
    <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"
diff --git a/tests/ref/iframe/simple_inline_width_percentage_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_percentage_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_width_percentage_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width_percentage_ref.html
diff --git a/tests/ref/iframe/simple_inline_width_ref.html b/tests/wpt/mozilla/tests/css/iframe/simple_inline_width_ref.html
similarity index 100%
rename from tests/ref/iframe/simple_inline_width_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/simple_inline_width_ref.html
diff --git a/tests/ref/iframe/size_attributes.html b/tests/wpt/mozilla/tests/css/iframe/size_attributes.html
similarity index 78%
rename from tests/ref/iframe/size_attributes.html
rename to tests/wpt/mozilla/tests/css/iframe/size_attributes.html
index 72e1d1d63d0..48faebca752 100644
--- a/tests/ref/iframe/size_attributes.html
+++ b/tests/wpt/mozilla/tests/css/iframe/size_attributes.html
@@ -1,6 +1,7 @@
 <!DOCTYPE html>
 <html>
 <head>
+<link rel=match href=size_attributes_ref.html>
 <style>
 body {
     background: purple;
diff --git a/tests/ref/iframe/size_attributes_ref.html b/tests/wpt/mozilla/tests/css/iframe/size_attributes_ref.html
similarity index 100%
rename from tests/ref/iframe/size_attributes_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/size_attributes_ref.html
diff --git a/tests/ref/iframe/size_attributes_vertical_writing_mode.html b/tests/wpt/mozilla/tests/css/iframe/size_attributes_vertical_writing_mode.html
similarity index 75%
rename from tests/ref/iframe/size_attributes_vertical_writing_mode.html
rename to tests/wpt/mozilla/tests/css/iframe/size_attributes_vertical_writing_mode.html
index c6b69388573..a1f6a98ddc7 100644
--- a/tests/ref/iframe/size_attributes_vertical_writing_mode.html
+++ b/tests/wpt/mozilla/tests/css/iframe/size_attributes_vertical_writing_mode.html
@@ -1,6 +1,7 @@
 <!DOCTYPE html>
 <html>
 <head>
+<link rel=match href=size_attributes_vertical_writing_mode_ref.html>
 <style>
 body {
     background: purple;
diff --git a/tests/ref/iframe/size_attributes_vertical_writing_mode_ref.html b/tests/wpt/mozilla/tests/css/iframe/size_attributes_vertical_writing_mode_ref.html
similarity index 100%
rename from tests/ref/iframe/size_attributes_vertical_writing_mode_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/size_attributes_vertical_writing_mode_ref.html
diff --git a/tests/ref/iframe/stacking_context.html b/tests/wpt/mozilla/tests/css/iframe/stacking_context.html
similarity index 86%
rename from tests/ref/iframe/stacking_context.html
rename to tests/wpt/mozilla/tests/css/iframe/stacking_context.html
index feeea572eaa..54e2b584c3c 100644
--- a/tests/ref/iframe/stacking_context.html
+++ b/tests/wpt/mozilla/tests/css/iframe/stacking_context.html
@@ -1,4 +1,5 @@
 <!DOCTYPE html>
+<link rel=match href=stacking_context_ref.html>
 <style>
 iframe {
     position: absolute;
diff --git a/tests/ref/iframe/stacking_context_position_a.html b/tests/wpt/mozilla/tests/css/iframe/stacking_context_position_a.html
similarity index 77%
rename from tests/ref/iframe/stacking_context_position_a.html
rename to tests/wpt/mozilla/tests/css/iframe/stacking_context_position_a.html
index be4b870407f..262e573e4a8 100644
--- a/tests/ref/iframe/stacking_context_position_a.html
+++ b/tests/wpt/mozilla/tests/css/iframe/stacking_context_position_a.html
@@ -1,3 +1,4 @@
+<link rel=match href=stacking_context_position_ref.html>
 <body style="background:tan">
     <div style="transform: translateX(0px)">
         <iframe src="data:text/html,%3Cspan%3EJust%20a%20simple%20little%20iframe.%3C%2Fspan%3E"></iframe>
diff --git a/tests/ref/iframe/stacking_context_position_ref.html b/tests/wpt/mozilla/tests/css/iframe/stacking_context_position_ref.html
similarity index 100%
rename from tests/ref/iframe/stacking_context_position_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/stacking_context_position_ref.html
diff --git a/tests/ref/iframe/stacking_context_ref.html b/tests/wpt/mozilla/tests/css/iframe/stacking_context_ref.html
similarity index 100%
rename from tests/ref/iframe/stacking_context_ref.html
rename to tests/wpt/mozilla/tests/css/iframe/stacking_context_ref.html