Auto-generate casting helper functions for CSSRule subclasses.

Introduce DEFINE_CSS_RULE_TYPE_CASTS macro, and use it for all of CSSRule
subclasses.
Replace existing static_cast<CSSFooRule*> with toCSSFooRule().

This CL is helpful to detect bad casts.

BUG=309516
TEST=none; No behavior changes.

Review URL: https://codereview.chromium.org/108923005

git-svn-id: svn://svn.chromium.org/blink/trunk@163508 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fixed bookkeeping bug in management of dimensions of mailbox's texture.

This fixes several problems with rapid resizing of WebGL-rendered canvases.

Also added a WebGL conformance test for this bug.

BUG=299371
TEST=DrawingBufferTest.verifyResizingProperlyAffectsMailboxes

Review URL: https://codereview.chromium.org/105123003

git-svn-id: svn://svn.chromium.org/blink/trunk@163509 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert of https://codereview.chromium.org/110663003/
Reason for revert: The new code is unreadable.

TBR=haraken@chromium.org,ch.dumez@samsung.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/98853012

git-svn-id: svn://svn.chromium.org/blink/trunk@163511 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Show delete button in input[type=search] only if the field is editable and focused/hovered.

Also, we show/hide the button with CSS opacity property instead of CSS
visibility property when the value emptiness is changed.  This helps Web
authors to add CSS transition.

BUG=325496
TEST=automated.

Review URL: https://codereview.chromium.org/100823012

git-svn-id: svn://svn.chromium.org/blink/trunk@163512 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Android: Fix a bug that unselecting the first <option> in <select multiple> selecting the first <option> again.

<select multiple> has menulist appearance on Android. Though menulist always
select an option, <select multiple> should have API compatibility with
non-Android.

BUG=325038
TEST=automated

Review URL: https://codereview.chromium.org/102663004

git-svn-id: svn://svn.chromium.org/blink/trunk@163513 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [Elements] Improve shadow DOM representation

Shadow DOM is no longer dimmed and has a vertical bar to its left.

R=aandrey, eustas, pfeldman
BUG=305399

Review URL: https://codereview.chromium.org/75413009

git-svn-id: svn://svn.chromium.org/blink/trunk@163515 bbb929c8-8fbe-4397-9dbb-9b2b20218538