Web Animations: Expose timeline currentTime in IDL

AnimationTimeline has currentTime of type double - the time value for
this timeline.

Web Animations spec, section 5.1 The AnimationTimeline interface
http://dev.w3.org/fxtf/web-animations/#the-animationtimeline-interface


BUG=357432

Review URL: https://codereview.chromium.org/215043007

git-svn-id: svn://svn.chromium.org/blink/trunk@170513 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add a comment about UseCounter availability in M35 branch.

We have similar comments for M33 and M34.

NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/220513002

git-svn-id: svn://svn.chromium.org/blink/trunk@170514 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Style changes shouldn't cause RenderLayerCompositor to rebuild its tree

Before this CL, if you changed the style on a RenderLayer that was directly
composited, we would trigger a rebuild of the entire compositing tree as part
of the "chicken-egg hacks." There's no reason for that. Instead, we simply need
to do a geometry update after changing style.

This makes the compositing update in the calculator faster by 7%.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/220193003

git-svn-id: svn://svn.chromium.org/blink/trunk@170515 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: have RepeatEvent::trace() delegate to Event::trace()

For consistency, have RepeatEvent 'upcall' to Event when tracing.

R=
BUG=340522

Review URL: https://codereview.chromium.org/219283007

git-svn-id: svn://svn.chromium.org/blink/trunk@170516 bbb929c8-8fbe-4397-9dbb-9b2b20218538