Assert that Length::blend is called with specified values

The checks in Length::blend for non-specified values were for the old
CSS animations/transitions code paths which have now been removed. We
should no longer get into Length::blend with non-specified values.

BUG=

Review URL: https://codereview.chromium.org/234413004

git-svn-id: svn://svn.chromium.org/blink/trunk@171426 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Avoid hash table lookup for every attribute

We should avoid looking at the hash table of event handler attributes
for all attributes which don't start with "on", which is most attributes.

Review URL: https://codereview.chromium.org/228943008

git-svn-id: svn://svn.chromium.org/blink/trunk@171427 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert of Gardening: fast/workers/worker-multi-startup.html is crashing on Linux (https://codereview.chromium.org/226653003/)

Reason for revert:
passes again

Original issue's description:
> Gardening: fast/workers/worker-multi-startup.html is crashing on Linux
> 
> Appears to be from a v8 roll.
> 
> TBR=dcarney@chromium.org
> BUG=362146
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=171291

TBR=dcarney@chromium.org,leviw@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=362146

Review URL: https://codereview.chromium.org/236773002

git-svn-id: svn://svn.chromium.org/blink/trunk@171428 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Mark http/tests/images/webp-partial-load.html as flaky in all platforms.

This test looks flaky also in linux.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=http%2Ftests%2Fimages%2Fwebp-partial-load.html

TBR=leviw@chromium.org
BUG=313846

Review URL: https://codereview.chromium.org/236793002

git-svn-id: svn://svn.chromium.org/blink/trunk@171429 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: remove references to fields absent in protocol.json's CSSStyle

TBR=apavlov,pfeldman

Review URL: https://codereview.chromium.org/236613003

git-svn-id: svn://svn.chromium.org/blink/trunk@171430 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove dead code from HTMLElement::parseAttribute

Element::parseAttribute does nothing so there's no reason to have a
special case to call it for id, class and style attributes.

Review URL: https://codereview.chromium.org/236363005

git-svn-id: svn://svn.chromium.org/blink/trunk@171431 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove unused WebScreenInfoFactory.

BUG=90115

Review URL: https://codereview.chromium.org/235503008

git-svn-id: svn://svn.chromium.org/blink/trunk@171432 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: support importing layer tree from trace snapshots.

BUG=

Review URL: https://codereview.chromium.org/224843014

git-svn-id: svn://svn.chromium.org/blink/trunk@171433 bbb929c8-8fbe-4397-9dbb-9b2b20218538