Disable automatic font fallback of SkFontHost_android when building for WebKit

The internal font fallback mechanism prevents WebKit from getting
the properties of the actually used font. Disable the internal fallback
mechanism when building for WebKit and add SkGetFallbackFamilyNameForChar()
to let the upper level know the fallback font for individial characters.

This commits a change that was submitted for review by...
wangxianzhu1 @ https://codereview.appspot.com/6572059/

BUG=913 (http://code.google.com/p/skia/issues/detail?id=913)

Review URL: https://codereview.appspot.com/6640048

git-svn-id: http://skia.googlecode.com/svn/trunk@5866 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed