layout: Round clientTop, etc queries to pixels properly (#31187)

* layout: Round getClientRect queries to pixels properly

Instead of just flooring all pixels in getClientRect queries, we should
round the rectangle.

* Fix scrollWidth/scrollHeight too, and tests

* Tests passing

* Test expectation for legacy layout

---------

Co-authored-by: Oriol Brufau <obrufau@igalia.com>

tests/wpt/meta/MANIFEST.json

@@ -562330,6 +562330,13 @@
        {}
       ]
      ],
+     "subpixel-sizes-and-offsets.tentative.html": [
+      "d198b9dde60c8cac16241c412d3e55f772166010",
+      [
+       null,
+       {}
+      ]
+     ],
      "table-border-collapse-client-width-height.html": [
       "a7a1a435b2279ccb07136ed295dcc25b38c2c87c",
       [

tests/wpt/meta/css/css-tables/fractional-percent-width.html.ini

@@ -1,6 +0,0 @@
-[fractional-percent-width.html]
-  [.cell 2]
-    expected: FAIL
-
-  [.cell 3]
-    expected: FAIL

tests/wpt/meta/css/cssom-view/subpixel-sizes-and-offsets.tentative.html.ini

@@ -0,0 +1,24 @@
+[subpixel-sizes-and-offsets.tentative.html]
+  [clientWidth, offsetWidth and scrollWidth round 5.5 to 6]
+    expected: FAIL
+
+  [clientWidth, offsetWidth and scrollWidth round 5.9 to 6]
+    expected: FAIL
+
+  [clientHeight, offsetHeight and scrollHeight round 5.1 to 5]
+    expected: FAIL
+
+  [clientHeight, offsetHeight and scrollHeight round 5.5 to 6]
+    expected: FAIL
+
+  [clientHeight, offsetHeight and scrollHeight round 5.9 to 6]
+    expected: FAIL
+
+  [clientLeft and clientTop don't round 44.9]
+    expected: FAIL
+
+  [clientLeft and clientTop don't round 44.5]
+    expected: FAIL
+
+  [clientLeft and clientTop don't round 44.1]
+    expected: FAIL

tests/wpt/meta/css/cssom-view/table-border-collapse-client-width-height.html.ini

@@ -1,3 +0,0 @@
-[table-border-collapse-client-width-height.html]
-  [Table's clientWidth/Height and OffsetWidth/Height should be the same]
-    expected: FAIL

tests/wpt/meta/css/cssom-view/table-border-separate-client-width-height.html.ini

@@ -1,3 +0,0 @@
-[table-border-separate-client-width-height.html]
-  [Table's clientWidth/Height and OffsetWidth/Height should be the same]
-    expected: FAIL