[DirectWrite] Use embedded bitmap where available

Set the Skia kEmbeddedBitmapText_Flag for small (<= 24px) font sizes
thereby instructing Skia to use the embedded bitmap should one be
available for the requested font and size.

This replaces the hard-coded list of fonts requireing full hinting and
the per-script min size for anti-aliased text rendering.

R=bungeman@chromium.org,jam@chromium.org
BUG=356823,365208

Review URL: https://codereview.chromium.org/266913013

git-svn-id: svn://svn.chromium.org/blink/trunk@173353 bbb929c8-8fbe-4397-9dbb-9b2b20218538