Web Animations CSS: Implement AnimatableValue::equals

This function is intended to be used for the upcoming transitions
implementation on the Web Animations model. This will be used for
seeing if the computed value for an element has been updated, and
comparing to the start and goal of running transitions.

This is slightly more expensive than comparing values directly off
RenderStyles (CSSPropertyAnimation), but is probably a cleaner way
of implementing this (we can later see if the extra indirection is
going to affect performance, in particular for transition all).

The behaviour here on comparing ShapeValue and ClipPathOperation is
slightly changed from CSSPropertyAnimation, and we now will compare
the objects themselves instead of just pointers.

BUG=303430

Review URL: https://codereview.chromium.org/25813004

git-svn-id: svn://svn.chromium.org/blink/trunk@159097 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Blink gardening: rebase expectation for device-metrics-fit-window.html

TBR=enne@chromium.org
BUG=N/A
NOTRY=true

Review URL: https://codereview.chromium.org/26441003

git-svn-id: svn://svn.chromium.org/blink/trunk@159098 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix compile errors from moving core/platform/audio

This CL should resolve a couple compile errors from moving core/platform/audio
to platform/audio. There is at least one more compile error to resolve.

git-svn-id: svn://svn.chromium.org/blink/trunk@159099 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix build after core/platform/audio move

This file was missing its primary header and therefore couldn't see the
PLATFORM_EXPORT declaration.

git-svn-id: svn://svn.chromium.org/blink/trunk@159100 bbb929c8-8fbe-4397-9dbb-9b2b20218538