Don't use bytecode hinted metrics when not bytecode hinting.

GDI, DirectWrite, and CoreText don't need or want separate VDMX parsing.
FreeType should contain this code (and apply it only when asking for hinted
font metrics) but doesn't.

This VDMX code was written when this path was FreeType only and was written in
an effort to make the FreeType platform look *exactly* like the Windows platform
(in an effort to reduce layout test results). Basically, the VDMX table is a
table of hinted font metrics (cached ascent, descent). When one draws with
hinted glyphs they should be used, if one draws with unhinted glyphs they
shouldn't be used. On all other platforms, this is already taken care of. On
GDI there is no real means of turning off bytecode hinting, and GDI always
returns metrics from the VDMX table when available already. CoreText and
DirectWrite basically ignore the bytecode hints and also ignore the VDMX table
when reporting metrics. However, FreeType does not currently do this. It
provides a way to draw with hinted or unhinted glyphs, but provides no means to
access the hinted ascent and descent (the VDMX table). This WebKit code was
added to work around this issue, but because it is always enabled it is forcing
hinted font metrics when drawing with unhinted glyphs. This is why
underscores were disappearing; the hinted metrics had a smaller descent than
unhinted metrics and the unhinted underscore fell below this smaller hinted
descent. As a result, the next line overdraws the underscore.

BUG=41457
R=eae@chromium.org

Review URL: https://codereview.chromium.org/13800019

git-svn-id: svn://svn.chromium.org/blink/trunk@165862 bbb929c8-8fbe-4397-9dbb-9b2b20218538