Auto merge of #27505 - utsavoza:ugo/issue-24718/05-08-2020, r=jdm

Do not load srcdoc iframes synchronously

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #24718
- [x] There are tests for these changes

tests/wpt/metadata/cookies/cookie-enabled-noncookie-frame.html.ini

@@ -0,0 +1,5 @@
+[cookie-enabled-noncookie-frame.html]
+  expected: TIMEOUT
+  [navigator.cookieEnabled behavior on frames without cookie access]
+    expected: TIMEOUT
+

tests/wpt/metadata/custom-elements/perform-microtask-checkpoint-before-construction.html.ini

@@ -1,7 +0,0 @@
-[perform-microtask-checkpoint-before-construction.html]
-  [HTML parser must perform a microtask checkpoint before constructing a custom element]
-    expected: FAIL
-
-  [HTML parser must perform a microtask checkpoint before constructing a custom element during the adoption agency algorithm]
-    expected: FAIL
-

tests/wpt/metadata/html/browsers/sandboxing/sandbox-disallow-scripts-via-unsandboxed-popup.tentative.html.ini

@@ -1,4 +1,5 @@
 [sandbox-disallow-scripts-via-unsandboxed-popup.tentative.html]
+  expected: ERROR
   [Sandboxed => unsandboxed popup]
-    expected: FAIL
+    expected: TIMEOUT
 

tests/wpt/metadata/html/interaction/focus/the-autofocus-attribute/skip-not-fully-active.html.ini

@@ -1,3 +0,0 @@
-[skip-not-fully-active.html]
-  [Autofocus element in not-fully-active document should be skipped while flusing.]
-    expected: FAIL

tests/wpt/metadata/referrer-policy/generic/sandboxed-iframe-with-opaque-origin.html.ini

@@ -1,5 +1,9 @@
 [sandboxed-iframe-with-opaque-origin.html]
   type: testharness
+  expected: TIMEOUT
   [Sandboxed iframe with opaque origin doesn't send referrers.]
-    expected: FAIL
+    expected: TIMEOUT
+
+  [Sandboxed iframe with tuple origin sends referrers.]
+    expected: TIMEOUT