Always use GDI implementation of GlyphPage::fill on Windows

The switch to use Skia for font metrics on windows in r158845 caused
a set of regressions for some non-latin pages. Most noticeable being
a 50+% regression on the intl_ja_zh page cycler on XP (about 20% on
Windows 7).

Until the root cause can be identified fall back on the GDI
implementation regardless of the Skia/GDI flag.

BUG=304868

Review URL: https://codereview.chromium.org/27711008

git-svn-id: svn://svn.chromium.org/blink/trunk@159931 bbb929c8-8fbe-4397-9dbb-9b2b20218538