Generate toCSSFooValue() for CSSFooValues

As a step of generating toCSSFooValue(), this cl adds toCSSFooValue() for some CSS child values. (CSSCanvasValue, CSSCrossfadeValue, CSSImageGeneratorValue, CSSImageValue, CSSInitialValue, CSSTimingFunctionValue, CSSCubicBezierTimingFunctionValue and CSSStepsTimingFunctionValue)

This will help to detect bad type casts. To support some toCSSFooValue(), isCanvasValue(), isUnicodeRangeValue(), and isCrossfadeValue() are addeded to CSSValue.h.

BUG=N/A

Review URL: https://codereview.chromium.org/25434004

git-svn-id: svn://svn.chromium.org/blink/trunk@158916 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations CSS: Handle -webkit-column-count property

BUG=240653
R=dstockwell

Review URL: https://codereview.chromium.org/25565003

git-svn-id: svn://svn.chromium.org/blink/trunk@158917 bbb929c8-8fbe-4397-9dbb-9b2b20218538
IDL compiler: KeepAttributeAliveForGC

KeepAttributeAliveForGC is already supported by the IDL compiler.
This CL just adds test cases (including for the usual is_keep_attribute_alive path),
and refactors the code slightly to make it more generic.
(Going out of alphabetical order b/c code already there but untested.)

There is only one actual use case of this:
Source/core/html/HTMLTemplateElement.idl
[KeepAttributeAliveForGC] readonly attribute DocumentFragment content;

Normally this attribute would not be kept alive, b/c DocumentFragment is a DOM Node type;
these are not kept alive, with the explanation being:
"Node lifetime is managed by object grouping."
There is no explanation of why this extended attribute is used on this one attribute.

Docs:
https://sites.google.com/a/chromium.org/dev/blink/webidl/blink-idl-extended-attributes#TOC-KeepAttributeAliveForGC-a-

BUG=239771

Review URL: https://codereview.chromium.org/25507007

git-svn-id: svn://svn.chromium.org/blink/trunk@158918 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations CSS: Support animation of baseline-shift

BUG=257591
R=dstockwell

Review URL: https://codereview.chromium.org/25830005

git-svn-id: svn://svn.chromium.org/blink/trunk@158919 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[Android WebView] Fixed width set in the viewport tag must not be scaled by target-densitydpi

Legacy WebView only scales the layout width if it is set to 'device-width' or 'auto',
but not if it is set explicitly as a numeric value.

BUG=302974

Review URL: https://codereview.chromium.org/25356004

git-svn-id: svn://svn.chromium.org/blink/trunk@158920 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Break core/platform/network dependency on CSP

This CL just moves an enum from ContentSecurityPolicy into HTTPParsers.h

R=jochen@chromium.org
BUG=297477

Review URL: https://codereview.chromium.org/25983002

git-svn-id: svn://svn.chromium.org/blink/trunk@158921 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[Android WebView] In non-WideViewport mode, initial-scale < 1 must be ignored

From my experiments with the existing implementation, it turns out that in the
case when WideViewport is turned off, values of initial-scale < 1 are ignored in
most cases. The layout width is set to device-width (scaled according to
target-densitydpi). This also includes 'auto' initial-scale.

An exception from the rule is the case when width is set to device-width,
in which case the initial-scale is respected.

BUG=303189

Review URL: https://codereview.chromium.org/25353006

git-svn-id: svn://svn.chromium.org/blink/trunk@158922 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [CSSStyleModel] Do not send multiple computed style requests when requested synchronously

R=pfeldman, vsevik
BUG=295643

Review URL: https://codereview.chromium.org/23902052

git-svn-id: svn://svn.chromium.org/blink/trunk@158923 bbb929c8-8fbe-4397-9dbb-9b2b20218538