Initial patch for FontVariant, this is to support HalfWidth,
ThirdWidth, QuarterWidth and will take complex path
while rendering.

BUG=350404

Review URL: https://codereview.chromium.org/263363005

git-svn-id: svn://svn.chromium.org/blink/trunk@180241 bbb929c8-8fbe-4397-9dbb-9b2b20218538