Upgrade WebRender to e491e1ae637b2eed1e7195855d88357e5eb3ddf9 (#30323)

* Upgrade vendored version of WebRender

* Patch WebRender: upgrade version of gleam

* Restore hit testing implementation

* Fix WebRender warnings

* Adapt Servo to new WebRender

* Update results

* Add a workaround for #30313

This slightly expands text boundaries in order to take into account the
fact that layout isn't measuring glyph boundaries.

tests/wpt/mozilla/meta-legacy-layout/css/border-radius-image.html.ini

@@ -1,2 +1,2 @@
 [border-radius-image.html]
-  fuzzy: /_mozilla/css/border-radius-image-ref.html:63;696
+  expected: FAIL

tests/wpt/mozilla/meta-legacy-layout/css/pixel_snapping_position_a.html.ini

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

tests/wpt/mozilla/meta-legacy-layout/gfx-rs-gecko/opacity-background-1.html.ini

@@ -1,3 +0,0 @@
-[opacity-background-1.html]
-  expected:
-    if os == "linux": FAIL

tests/wpt/mozilla/meta-legacy-layout/mozilla/scroll_root.html.ini

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

tests/wpt/mozilla/meta/css/pixel_snapping_position_a.html.ini

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

tests/wpt/mozilla/meta/gfx-rs-gecko/opacity-background-1.html.ini

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

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

@@ -0,0 +1,3 @@
+[scrollBy.html]
+  [Ensure that the window.scrollBy function affects scroll position as expected]
+    expected: FAIL

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

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