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

third_party/WebKit/LayoutTests/FlagExpectations/enable-slimming-paint-v2

 # Expectations for slimming paint v2
 # See: https://docs.google.com/document/d/1QCM912Dr6u38DqyQqd7pxQxDy8FFOoWMMDq7uAXqKdA/view
 # We are focused on fast/, compositing/, and svg/ with all other directories skipped (for now).
 
 Bug(none) accessibility/ [ Skip ]
 Bug(none) animations/ [ Skip ]
 Bug(none) app_banner/ [ Skip ]
 Bug(none) battery-status/ [ Skip ]
 Bug(none) bindings/ [ Skip ]
 Bug(none) bluetooth/ [ Skip ]
@@ skipping 520 matching lines @@
 Bug(none) fast/box-shadow/box-shadow-transformed.html [ Failure ]
 Bug(none) fast/box-shadow/box-shadow.html [ Failure ]
 Bug(none) fast/box-shadow/scaled-box-shadow.html [ Failure ]
 Bug(none) fast/box-sizing/box-sizing.html [ Failure ]
 Bug(none) fast/box-sizing/panels-one.html [ Failure ]
 Bug(none) fast/box-sizing/panels-two.html [ Failure ]
 Bug(none) fast/canvas/alpha.html [ Failure ]
 Bug(none) fast/canvas/canvas-composite-video.html [ Failure ]
 Bug(none) fast/canvas/canvas-css-clip-path.html [ Failure ]
 Bug(none) fast/canvas/webgl/pixelated.html [ Failure ]
+crbug.com/668342 fast/clip/010.html [ Failure ]
 Bug(none) fast/clip/nestedTransparencyClip.html [ Failure ]
 Bug(none) fast/clip/outline-overflowClip.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-clip.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-combinations.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-composited-parent.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-composited.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-fixed-position.html [ Failure ]
 Bug(none) fast/clip/overflow-border-radius-transformed.html [ Failure ]
 Bug(none) fast/css-generated-content/014.html [ Failure ]
 Bug(none) fast/css-generated-content/table-parts-before-and-after.html [ Failure ]
@@ skipping 689 matching lines @@
 Bug(none) svg/custom/getscreenctm-in-scrollable-div-area.xhtml [ Failure ]
 Bug(none) svg/custom/getscreenctm-in-scrollable-svg-area.xhtml [ Failure ]
 Bug(none) svg/custom/gradient-deep-referencing.svg [ Failure ]
 Bug(none) svg/custom/gradient-rotated-bbox.svg [ Failure ]
 Bug(none) svg/custom/gradient-stop-corner-cases.svg [ Failure ]
 Bug(none) svg/custom/gradient-with-1d-boundingbox.svg [ Failure ]
 Bug(none) svg/custom/grayscale-gradient-mask-2.svg [ Failure ]
 Bug(none) svg/custom/grayscale-gradient-mask.svg [ Failure ]
 Bug(none) svg/custom/group-opacity.svg [ Failure ]
 Bug(none) svg/custom/image-with-preserveAspectRatio-none.html [ Failure ]
+Bug(none) svg/custom/image-with-transform-clip-filter.svg [ Failure ]
 Bug(none) svg/custom/inline-svg-in-xhtml.xml [ Failure ]
 Bug(none) svg/custom/invalid-css.svg [ Failure ]
 Bug(none) svg/custom/invalid-stroke-hex.svg [ Failure ]
 Bug(none) svg/custom/junk-data.svg [ Failure ]
 Bug(none) svg/custom/linking-a-03-b-all.svg [ Failure ]
 Bug(none) svg/custom/linking-a-03-b-transform.svg [ Failure ]
 Bug(none) svg/custom/linking-a-03-b-viewBox-transform.svg [ Failure ]
 Bug(none) svg/custom/linking-a-03-b-viewBox.svg [ Failure ]
 Bug(none) svg/custom/linking-uri-01-b.svg [ Failure ]
 Bug(none) svg/custom/load-non-wellformed.svg [ Failure ]
@@ skipping 68 matching lines @@
 Bug(none) svg/custom/use-on-symbol-inside-pattern.svg [ Failure ]
 Bug(none) svg/custom/use-on-symbol.svg [ Failure ]
 Bug(none) svg/custom/use-on-text.svg [ Failure ]
 Bug(none) svg/custom/use-on-use.svg [ Failure ]
 Bug(none) svg/custom/use-property-changes-through-dom.svg [ Failure ]
 Bug(none) svg/custom/use-property-changes-through-svg-dom.svg [ Failure ]
 Bug(none) svg/custom/use-referencing-nonexisting-symbol.svg [ Failure ]
 Bug(none) svg/custom/use-transform.svg [ Failure ]
 Bug(none) svg/custom/viewBox-hit.svg [ Failure ]
 Bug(none) svg/custom/viewbox-syntax.svg [ Failure ]
+Bug(none) svg/custom/viewport-clippath-invalidation.html [ Failure ]
 Bug(none) svg/custom/visibility-override-clip.svg [ Failure ]
 Bug(none) svg/custom/visibility-override-mask.svg [ Failure ]
 Bug(none) svg/custom/visited-link-color.svg [ Failure ]
 Bug(none) svg/custom/width-full-percentage.svg [ Failure ]
 Bug(none) svg/custom/zero-path-square-cap-rendering2.svg [ Failure ]
 Bug(none) svg/custom/zoomed-background-alignment.html [ Failure ]
 Bug(none) svg/dom/complex-svgView-specification.html [ Failure ]
 Bug(none) svg/dom/css-transforms.xhtml [ Failure ]
 Bug(none) svg/dom/SVGStringList-basics.xhtml [ Failure ]
 Bug(none) svg/dynamic-updates/SVG-dynamic-css-transform.html [ Failure ]
@@ skipping 851 matching lines @@
 # fast/forms/search/search-vertical-alignment.html
 # fast/forms/search/searchfield-heights.html
 # fast/forms/text/text-font-height-mismatch.html
 # fast/forms/text/textfield-overflow-by-value-update.html
 # fast/replaced/width100percent-searchfield.html
 #
 # SPv2 correctly positions a background clip that includes the transformed size of div #two.
 # SPv1 does not understand how to apply transforms properly in PaintLayerClipper (the issue is
 # also tracked in crbug.com/548184).
 # transforms/transform-overflow.html
+
+# Subpixel adjustments due to differences in compositing
+crbug.com/668342 fast/pagination/auto-height-with-break.html [ Failure ]
+crbug.com/668342 svg/custom/non-scaling-stroke-update.svg [ Failure ]
+crbug.com/668342 fast/css/transform-default-parameter.html [ Failure ]
+crbug.com/668342 svg/custom/use-css-events.svg [ Failure ]
+crbug.com/668342 svg/text/text-layout-crash.html [ Failure ]
+crbug.com/668342 fast/multicol/span/invalid-spanner-in-transform.html [ Failure ]
+crbug.com/668342 images/color-profile-iframe.html [ Failure ]