Remove custom style building for font-variant-ligatures.

This patch uses a small, in-flight structure 'VariantLigatures' to
transfer the font-variant-ligatures data during style building.

This makes font style building less custom, and it removes some use of
CSSValue inside FontBuilder.

Review URL: https://codereview.chromium.org/447443003

git-svn-id: svn://svn.chromium.org/blink/trunk@179588 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Implement basic interfaces and attributes for DOMMatrix.

The DOMMatrix can represent a mathmetical matrix with the purpose of
describing transformations in a graphical context.

The specification:
  http://dev.w3.org/fxtf/geometry/
  
Intent to Implement:
  https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/V_bJNtOg0oM

BUG=388780

Review URL: https://codereview.chromium.org/426063007

git-svn-id: svn://svn.chromium.org/blink/trunk@179589 bbb929c8-8fbe-4397-9dbb-9b2b20218538