DevTools: Eliminate dead code from StylesSidebarPane.js

R=pfeldman, vsevik

Review URL: https://chromiumcodereview.appspot.com/23904021

git-svn-id: svn://svn.chromium.org/blink/trunk@157953 bbb929c8-8fbe-4397-9dbb-9b2b20218538
New parser mode for CSSOM @viewport descriptors.

CSSOM value and descriptor parsing for @viewport used parsing rules for normal
CSS property declarations instead, meaning width and height were not parsed as
shorthands.

This is an issue for other CSSOM access to other descriptors too, like for
@font-face.

This fix is minimal for the @viewport case and intended for feedback on the
general approach. I considered not adding new parser modes, but use a bit in
StylePropertySet to indicate a CSSParserMode or a descriptor mode and let two
bits store the mode. With both the current changes and the split, a descriptor
mode would implicitly be strict.

BUG=272718

Review URL: https://chromiumcodereview.appspot.com/22917005

git-svn-id: svn://svn.chromium.org/blink/trunk@157955 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Enable fixed SVG LayoutTests

These previously crashing LayoutTests were fixed in r157801.

BUG=288771
BUG=266213

Review URL: https://chromiumcodereview.appspot.com/23703015

git-svn-id: svn://svn.chromium.org/blink/trunk@157956 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Provide matched CSS rules for pseudo elements

This change makes rules with selectors like "div:before" be matched rules for the
respective :before pseudo elements, as returned by CSS.getMatchedStylesForNode.

R=pfeldman
BUG=180291

Review URL: https://chromiumcodereview.appspot.com/23757044

git-svn-id: svn://svn.chromium.org/blink/trunk@157958 bbb929c8-8fbe-4397-9dbb-9b2b20218538