Implement support for numeric font-weights on Windows

Implement support for numeric font-weights (i.e. 100..900) on platforms
using SkFontMgr by switching to the new matchFamilyStyle API instead of
the old legacyCreateTypeface one.

Currently SkFontMgr is only used on Windows.

R=dglazkov@chromium.org
BUG=394692
TEST=fast/text/font-weight.html

Review URL: https://codereview.chromium.org/470443004

git-svn-id: svn://svn.chromium.org/blink/trunk@180279 bbb929c8-8fbe-4397-9dbb-9b2b20218538