Enable universal accelerated overflow scroll

LayoutTests/TestExpectations

 # This directly has manual tests that don't have to run with run-webkit-tests
 crbug.com/359838 http/tests/ManualTests/ [ Skip ]
 
 crbug.com/258949 fast/filesystem/workers/file-writer-truncate-extend.html [ Failure Pass ]
 
 crbug.com/307782 [ Win ] http/tests/cache/stopped-revalidation.html [ Pass Timeout ]
 crbug.com/316146 [ XP ] http/tests/cache/cached-main-resource.html [ Pass Timeout ]
 
 # Transient - XHR mixed content type revert will be restored.
 crbug.com/305303 http/tests/security/mixedContent/insecure-sync-post-xhr-allowed.html [ Failure Pass ]
@@ skipping 83 matching lines @@
 crbug.com/310679 [ Mac ] compositing/rubberbanding/transform-overhang-s.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] compositing/rubberbanding/transform-overhang-se.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] compositing/rubberbanding/transform-overhang-size-change.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] compositing/rubberbanding/transform-overhang-sw.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] compositing/rubberbanding/transform-overhang-w.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] fast/events/scale-and-scroll-iframe-body.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] fast/events/scale-and-scroll-iframe-window.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] fast/frames/frame-set-rotation-hit.html [ ImageOnlyFailure Pass ]
 crbug.com/310679 [ Mac ] fast/frames/frame-set-scaling-hit.html [ ImageOnlyFailure Pass ]
 crbug.com/318434 virtual/gpu/compositedscrolling/scrollbars/custom-scrollbar-with-incomplete-style.html [ ImageOnlyFailure ]
-crbug.com/346134 [ Linux ] virtual/gpu/compositedscrolling/overflow/invisible-descendants-should-not-affect-opt-in.html [ Pass Failure ]
 
 # Tests failing since applyPageScaleFactorInCompositor enabled
 crbug.com/225184 fast/repaint/relayout-fixed-position-after-scale.html [ ImageOnlyFailure ]
 
 # Pixel tests for RTL iframe scrollbar is erroneous. Cannot observe on actual browser.
 # Temporarily marking the flaky set below as NeedsManualRebaseline, so we can grab results
 # from the bots, rebaseline, and re-mark them out as flaky.
 #crbug.com/338794 [ Mac ] compositing/rtl/rtl-iframe-absolute-overflow.html [ NeedsManualRebaseline ]
 #crbug.com/338794 [ Mac ] compositing/rtl/rtl-iframe-absolute-overflow-scrolled.html [ NeedsManualRebaseline ]
 #crbug.com/338794 [ Mac ] compositing/rtl/rtl-iframe-fixed-overflow.html [ NeedsManualRebaseline ]
@@ skipping 430 matching lines @@
 crbug.com/307777 [ Android ] http/tests/download/inherited-encoding-form-submission-result.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] http/tests/security/no-javascript-refresh.php [ Timeout Pass ]
 crbug.com/307777 [ Android ] storage/quota/storagequota-query-usage.html [ Failure Timeout Pass ]
 crbug.com/307777 [ Android ] svg/foreignObject/absolute-position-foreign-object-child-crash.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] svg/in-html/svg-assert-failure-percentage.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] tables/hittesting/filltable-levels.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] virtual/softwarecompositing/overflow/get-transform-from-non-box-container.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] webaudio/stereo2mono-down-mixing.html [ Timeout Pass ]
 crbug.com/307777 [ Android ] webexposed/custom-elements.html [ Timeout Pass ]
 
+# Expectations changes due to switiching to "universal" accelerated overflow scrolling. The bottom three
+# are pixel differences due to anti-aliasing changes due to different layer promotion, the rest are due
+# to GraphicsLayer tree topology changes.
+crbug.com/249354 compositing/overflow/composited-scrolling-paint-phases.html [ NeedsRebaseline ]
+crbug.com/249354 compositing/overflow/universal-accelerated-overflow-scroll.html [ NeedsRebaseline ]
+crbug.com/249354 compositing/overflow/scrolling-content-clip-to-viewport.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/composited-scrolling-paint-phases.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/content-loses-scrollbars.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/universal-accelerated-overflow-scroll.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/scrolling-content-clip-to-viewport.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/overflow-scroll.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/softwarecompositing/overflow/composited-scrolling-paint-phases.html [ NeedsRebaseline ]
+crbug.com/249354 [ Android Linux Win ] virtual/softwarecompositing/overflow/universal-accelerated-overflow-scroll.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/softwarecompositing/overflow/scrolling-content-clip-to-viewport.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/nested-render-surfaces.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/nested-render-surfaces-with-intervening-clip.html [ NeedsRebaseline ]
+crbug.com/249354 virtual/gpu/compositedscrolling/overflow/nested-render-surfaces-with-rotation.html [ NeedsRebaseline ]
+
+# Exceeds the number of file descriptors allowed when allocating shared bitmaps.
+crbug.com/351897 [ Mac ] virtual/softwarecompositing/overflow/universal-accelerated-overflow-scroll.html [ Crash Pass ]
+
 crbug.com/363280 [ Debug ] inspector-protocol/debugger/debugger-terminate-dedicated-worker-while-paused.html [ Crash Pass ]
 
 crbug.com/309675 compositing/gestures/gesture-tapHighlight-simple-longPress.html [ ImageOnlyFailure ]
 
 crbug.com/305345 fast/events/mouseover-mouseout.html [ Failure Pass ]
 
 # Android virtual suite shares the same expectation.
 crbug.com/100798 [ Debug ] virtual/android/fullscreen/full-screen-iframe-allowed.html [ Failure Pass ]
 crbug.com/100798 [ Debug ] virtual/android/fullscreen/full-screen-iframe-allowed-prefixed.html [ Failure Pass ]
 crbug.com/243782 virtual/android/fullscreen/full-screen-remove-ancestor.html [ Pass Timeout ]
@@ skipping 548 matching lines @@
 crbug.com/364946 [ Mac ] virtual/gpu/fast/hidpi/video-controls-in-hidpi.html [ Pass ImageOnlyFailure ]
 
 # Added in r171958 and timing out on some platforms ever since.
 crbug.com/308992 svg/as-object/sizing/svg-in-object-placeholder-height-auto.html [ Pass Timeout ]
 crbug.com/308992 svg/as-object/sizing/svg-in-object-placeholder-height-fixed.html [ Pass Timeout ]
 crbug.com/308992 svg/as-object/sizing/svg-in-object-placeholder-height-percentage.html [ Pass Timeout ]
 
 crbug.com/364991 [ Debug ] compositing/overflow/iframe-scroll-children.html [ Pass Crash ]
 crbug.com/364991 [ Debug ] virtual/softwarecompositing/overflow/iframe-scroll-children.html [ Pass Crash ]
 crbug.com/364991 [ Debug ] virtual/gpu/compositedscrolling/overflow/iframe-scroll-children.html [ Pass Crash ]