Implement merging non-composited paint property nodes in the PACompositor.

third_party/WebKit/LayoutTests/TestExpectations

 # Intentional failures to test the layout test system.
 Bug(intentional) [ Android Linux Win Mac10.10 Mac10.11 Retina ] harness-tests/crash.html [ Crash ]
 crbug.com/644303 [ Mac10.9 ] harness-tests/crash.html [ Crash Timeout ]
 Bug(intentional) harness-tests/timeout.html [ Timeout ]
 
 # ====== Oilpan-only failures from here ======
 # Most of these actually cause the tests to report success, rather than
 # failure. Expected outputs will be adjusted for the better once Oilpan
 # has been well and truly enabled always.
 
@@ skipping 25 matching lines @@
 # as we go. Please remove [ Pass ] lines instead of rebaselining these tests.
 crbug.com/537409 virtual/spv2/ [ Skip ]
 crbug.com/563667 virtual/spv2/fast/block/basic/001.html [ Pass ]
 crbug.com/580355 virtual/spv2/fast/block/basic/018.html [ Pass ]
 # Begin whitlelisted paint invalidation tests
 crbug.com/647831 virtual/spv2/paint/invalidation/margin.html [ Pass ]
 # End whitlelisted paint invalidation tests
 crbug.com/596780 virtual/spv2/compositing/framesets/composited-frame-alignment.html [ Pass ]
 crbug.com/596780 virtual/spv2/compositing/geometry/outline-change.html [ Pass ]
 crbug.com/600618 virtual/spv2/svg/custom/object-current-scale.html [ Pass ]
-crbug.com/600618 virtual/spv2/svg/custom/object-sizing-explicit-height.xhtml [ Pass ]
+
+# Re-add this once it rebaselines.
+# crbug.com/600618 virtual/spv2/svg/custom/object-sizing-explicit-height.xhtml [ Pass ]
 # SkiaBitLocker should avoid allocating huge offscreen buffer
 crbug.com/605812 [ Mac ] virtual/spv2/fast/overflow/overflow-height-float-not-removed-crash.html [ Skip ]
 crbug.com/605812 [ Mac ] virtual/spv2/fast/overflow/overflow-height-float-not-removed-crash2.html [ Skip ]
 crbug.com/619427 [ Linux ] virtual/spv2/fast/overflow/overflow-height-float-not-removed-crash3.html [ Pass Failure ]
 # --- End SPV2 Tests ---
 
 crbug.com/309675 compositing/gestures/gesture-tapHighlight-simple-longPress.html [ Failure ]
 
 crbug.com/504613 crbug.com/524248 paint/images/image-backgrounds-not-antialiased.html [ Skip ]
 
@@ skipping 634 matching lines @@
 crbug.com/520174 fast/events/message-port-start-and-close-different-microtask.html [ Failure Pass ]
 crbug.com/652536 fast/events/mouse-cursor-change-after-image-load.html [ Failure Pass ]
 crbug.com/520188 [ Win ] http/tests/local/fileapi/file-last-modified-after-delete.html [ Failure Pass ]
 crbug.com/520188 [ Win ] virtual/mojo-loading/http/tests/local/fileapi/file-last-modified-after-delete.html [ Failure Pass ]
 crbug.com/520611 [ Debug ] fast/filesystem/workers/file-writer-events-shared-worker.html [ Failure Pass ]
 crbug.com/520613 http/tests/cache/freshness-header.html [ Failure Pass ]
 crbug.com/520613 virtual/mojo-loading/http/tests/cache/freshness-header.html [ Failure Pass ]
 crbug.com/520194 http/tests/xmlhttprequest/timeout/xmlhttprequest-timeout-worker-overridesexpires.html [ Failure Pass ]
 crbug.com/520194 virtual/mojo-loading/http/tests/xmlhttprequest/timeout/xmlhttprequest-timeout-worker-overridesexpires.html [ Failure Pass ]
 
+crbug.com/668342 virtual/spv2/svg/custom/object-sizing-explicit-height.xhtml [ NeedsRebaseline ]
+
 crbug.com/410974 fast/scroll-behavior/scroll-customization/scrollstate-basic.html [ Pass Failure ]
 crbug.com/410974 fast/scroll-behavior/scroll-customization/scrollstate-consume-deltas.html [ Pass Failure ]
 crbug.com/410974 fast/scroll-behavior/scroll-customization/scrollstate-consume-deltas-throw.html [ Pass Failure ]
 crbug.com/410974 fast/scroll-behavior/scroll-customization/scrollstate-distribute-to-scroll-chain-descendant.html [ Pass Failure ]
 crbug.com/410974 fast/scroll-behavior/scroll-customization/touch-scroll-customization.html [ Pass Failure ]
 
 # The test will pass once the --enable-features=TouchpadAndWheelScrollLatching flag is enabled by default.
 crbug.com/526463 fast/events/wheel/mouse-wheel-scroll-latching.html [ Failure ]
 
 crbug.com/410974 virtual/threaded/fast/scroll-behavior/scroll-customization/scrollstate-basic.html [ Pass Failure ]
@@ skipping 1694 matching lines @@
 crbug.com/657748 imported/csswg-test/css-display-3/display-contents-table-001.html [ Failure ]
 crbug.com/657748 imported/csswg-test/css-display-3/display-contents-table-002.html [ Failure ]
 crbug.com/657748 imported/csswg-test/css-display-3/display-contents-text-only-001.html [ Failure ]
 
 # ====== End of display: contents tests ======
 
 crbug.com/676229 [ Linux ] plugins/mouse-click-plugin-clears-selection.html [ Failure Pass ]
 
 # Temporarily disable sharedarraybuffer test to land API change in v8
 crbug.com/676063 virtual/sharedarraybuffer/fast/workers/worker-sharedarraybuffer-transfer.html [ Pass Timeout ]