Only upload the changed area of the glyph cache, not the entire
bitmap. Note that we can't do the full-on optimization here of copying a sub-rect
of the bitmap because of GL ES 2 limitations, but we can at least copy the
horizontal stripe containing the dirty rect, which can still be a big
savings over uploading the entire bitmap.
Issue #7158326 Bad framerates on MR1 (Mako, Manta, Prime)
Change-Id: Iab38d53202650f757ead4658cf4287bdad2b3cb9
FontRenderer.h defined several classes and structures that now live
in the font/ folder. This will make the code easier to read and
maintain.
Change-Id: I3dc044e9bde1d6515f8704f5c72462877d279fe2
