Auto merge of #29706 - mrobinson:temporary-fix-for-scroll-root, r=jdm

Fix scrolling on root element

eca0acf459 uncovered a bug in the way that the scrolling area of `window` was calculated and broke scrolling on the root element. This change does two things in order to fix that:

1. Does a partial revert of eca0acf459 in order to get scrolling from script working again on the window object.
2. Has the compositor always generate a frame for scrolls starting from script and waits for them. This is speculative fix for flakiness in root scrolling tests on CI.

The changes to the compositor expose some hidden failures, which is why some tests are marked as failing now.

---
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- [x] `./mach test-tidy` does not report any errors
- [x] There are tests for these changes

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tests/wpt/metadata-layout-2020/css/cssom-view/long_scroll_composited.html.ini

@@ -1,2 +0,0 @@
-[long_scroll_composited.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/cssom-view/scrolling-quirks-vs-nonquirks.html.ini

@@ -34,3 +34,21 @@
 
   [scrollLeft/scrollTop on the HTML body element in non-quirks mode]
     expected: FAIL
+
+  [scroll() on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scrollBy() on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scrollLeft/scrollTop on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scroll() on the HTML body element in quirks mode]
+    expected: FAIL
+
+  [scrollBy() on the HTML body element in quirks mode]
+    expected: FAIL
+
+  [scrollLeft/scrollTop on the HTML body element in quirks mode]
+    expected: FAIL

tests/wpt/metadata-layout-2020/css/filter-effects/backdrop-filter-edge-behavior.html.ini

@@ -1,2 +0,0 @@
-[backdrop-filter-edge-behavior.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/filter-effects/filtered-html-is-not-container.html.ini

@@ -0,0 +1,2 @@
+[filtered-html-is-not-container.html]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/filter-effects/filtered-inline-is-container.html.ini

@@ -0,0 +1,2 @@
+[filtered-inline-is-container.html]
+  expected: FAIL

tests/wpt/metadata/css/css-position/sticky/position-sticky-bottom-002.html.ini

@@ -1,2 +0,0 @@
-[position-sticky-bottom-002.html]
-  expected: FAIL

tests/wpt/metadata/css/css-position/sticky/position-sticky-flexbox.html.ini

@@ -1,2 +0,0 @@
-[position-sticky-flexbox.html]
-  expected: FAIL

tests/wpt/metadata/css/css-position/sticky/position-sticky-rendering.html.ini

@@ -1,2 +0,0 @@
-[position-sticky-rendering.html]
-  expected: FAIL

tests/wpt/metadata/css/css-position/sticky/position-sticky-top-002.html.ini

@@ -1,2 +0,0 @@
-[position-sticky-top-002.html]
-  expected: FAIL

tests/wpt/metadata/css/cssom-view/long_scroll_composited.html.ini

@@ -1,2 +0,0 @@
-[long_scroll_composited.html]
-  expected: FAIL

tests/wpt/metadata/css/cssom-view/scrolling-quirks-vs-nonquirks.html.ini

@@ -34,3 +34,21 @@
 
   [scrollLeft/scrollRight of the content in non-quirks mode]
     expected: FAIL
+
+  [scroll() on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scrollBy() on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scrollLeft/scrollTop on the root element in non-quirks mode]
+    expected: FAIL
+
+  [scroll() on the HTML body element in quirks mode]
+    expected: FAIL
+
+  [scrollBy() on the HTML body element in quirks mode]
+    expected: FAIL
+
+  [scrollLeft/scrollTop on the HTML body element in quirks mode]
+    expected: FAIL

tests/wpt/metadata/css/filter-effects/filtered-inline-is-container.html.ini

@@ -0,0 +1,2 @@
+[filtered-inline-is-container.html]
+  expected: FAIL

tests/wpt/mozilla/meta/mozilla/scroll_root.html.ini

@@ -1,2 +0,0 @@
-[scroll_root.html]
-  expected: FAIL