Web Animations CSS: Only trigger CSS animation events on animation frame updates

No visible change in behavior. This will enable jitter in the timeline time
between a regular task and an animation-frame task if necessary. This also
enables events to work as expected once we allow access to AnimationPlayers 
generated for CSS Animations and Transitions to be exposed via the API.

Review URL: https://codereview.chromium.org/270063003

git-svn-id: svn://svn.chromium.org/blink/trunk@173453 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Removed the ability to create WebGL contexts with 'webkit-3d'

BUG=357296

Review URL: https://codereview.chromium.org/271493002

git-svn-id: svn://svn.chromium.org/blink/trunk@173454 bbb929c8-8fbe-4397-9dbb-9b2b20218538
PlaceHolder in TextArea should allow carriage return and line feed

As per current spec, placeholder should allow carriage return and line feed for text area. While placeholder should strip carriage return and line feed for input type=text.

BUG=367632
R=tkent, keishi1
TEST=Placeholder containing CR and LF are not stripped from the text for
type text area, while for input type text it is stripped.

Review URL: https://codereview.chromium.org/253853002

git-svn-id: svn://svn.chromium.org/blink/trunk@173455 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix flakiness on import-custom-element-in-master-and-grandchild.html

TBR=dominicc@chromium.org, dglazkov@chromium.org
BUG=365956

Review URL: https://codereview.chromium.org/273513002

git-svn-id: svn://svn.chromium.org/blink/trunk@173456 bbb929c8-8fbe-4397-9dbb-9b2b20218538