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This change enables PaintTouchActionRects by default. This is a
new implementation of how the blink->cc logic works for the css
touch-action feature. The big idea behind PaintTouchActionRects is to
compute touch-action rects during paint, in paint order, as part of the
background paint phase.

With this change we expect better performance (primarily a drop in
ScrollingCoordinator time: Blink.ScrollingCoordinator.UpdateTime) as
well as observable bug fixes (e.g., https://crbug.com/826746).

This patch has several small parts:
1) runtime_enabled_features.json5 makes PaintTouchActionRects as stable.
2) The paint-touchaction-rects expectations have been made the default.
3) The paint-touchaction-rects virtual test suite has been removed.
4) 6 tests have been marked as passing (fixed with this feature).

Bug: 836905
Change-Id: I2bc12b335e8762eafde882bc475982df7e74a7d1
Reviewed-on: https://chromium-review.googlesource.com/c/1313051Reviewed-by: Xida Chen <xidachen@chromium.org>
Reviewed-by: Xianda Sun <sunxd@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605710}