Cleanup: Add more conversion helpers for usage.

Adding toDeviceMotionEvent and toDeviceOrientationEvent conversion
functions to replace static_cast, and update toWheelEvent and toGestureEvent
so that they accept NULL argument for consistency.

R=tkent, jamesr
BUG=None
TEST=None; No behavior changes;

Review URL: https://codereview.chromium.org/26434002

git-svn-id: svn://svn.chromium.org/blink/trunk@159223 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use a reference to avoid a copy of Vector<Node*> in ShadowDOMSiblingTraversalStrategy's constructor.

Looks like a lifetime of Vector<Node*> siblings is longer than that of ShadowDOMSiblingTraversalStrategy.

Note that I couldn't find any *significant* performance gain in PerformanceTest/ShadowDOM/*.hmtl by this change, though.

BUG=None

Review URL: https://codereview.chromium.org/26658002

git-svn-id: svn://svn.chromium.org/blink/trunk@159224 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations CSS: -webkit-column-gap can't be negative

Follow up https://src.chromium.org/viewvc/blink?view=rev&revision=158780,
add a comment to the -webkit-column-gap interpolation test about the gap
value: it can't be negative [1].

[1] http://dev.w3.org/csswg/css-multicol/#column-gap

BUG=257591

Review URL: https://codereview.chromium.org/26541004

git-svn-id: svn://svn.chromium.org/blink/trunk@159225 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Fix CSS styles when showing accessor properties preview console.table.

The console.table did not show the "<exception>" label with red color style
after resolving an accessor property placeholder.

BUG=175898
R=pfeldman,vsevik

Review URL: https://codereview.chromium.org/26616004

git-svn-id: svn://svn.chromium.org/blink/trunk@159226 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add support for the column-fill property.

Note: This is only supported in the (new) region based multicol implementation.

With column-fill support, a lot of multicol tests need an update.
The old implementation behaved as if column-fill were 'auto', but the
initial value is 'balance', so now we need to be explicit about that.
For auto-height tests it doesn't really matter - such multicols are always
balanced anyway.

Already reviewed in WebKit by David Hyatt.
See https://bugs.webkit.org/show_bug.cgi?id=117693

BUG=302897

Review URL: https://codereview.chromium.org/25687002

git-svn-id: svn://svn.chromium.org/blink/trunk@159227 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix cue rendering test and include support for left/right alignment.

The test has been broken for a while somehow, but only because at some
point the code for computing the width got close to the current version
of the WebVTT specification and the alignment has an impact on the width
of the text (so not specifying the alignment determines the default
align:middle and in some cases the width gets zero, e.g. with position:100%)

The specification also got changed in the sense that it also supports
left and right values for cue alignment, which are now included in the test
case and supported in the code.

TEST=Update existing test case.
BUG=299752
R=acolwell,scherkus

Review URL: https://codereview.chromium.org/25155003

git-svn-id: svn://svn.chromium.org/blink/trunk@159228 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations CSS: Rename SVG property interpolation tests to use 'svg-' prefix

BUG=257591
R=noel

Review URL: https://codereview.chromium.org/26627003

git-svn-id: svn://svn.chromium.org/blink/trunk@159229 bbb929c8-8fbe-4397-9dbb-9b2b20218538