One more pass at getting half float texture configs correct.

Added in check for sized internal format.
Made choice between RED and ALPHA orthogonal to HALF_FLOAT and
HALF_FLOAT_OES.
Enabled rendertarget support on ES 2.0.

Review URL: https://codereview.chromium.org/805033002
Cleanup: Remove a bunch of SkFontHost.h includes (unused).

Nobody that is including SkFontHost is using SkFontHost API, so lets
remove this includes, since the API per se is deprecated.

BUG=None
R=reed@google.com

Review URL: https://codereview.chromium.org/803733006
Fix complexclip3 test on gpu

BUG=skia:3260
R=egdaniel@google.com

Review URL: https://codereview.chromium.org/813653003
rebaseline after perspective/conic fix

BUG=skia:
TBR=
NOTRY=True

Review URL: https://codereview.chromium.org/811383002
Various complex clip rebases

TBR=
NOTRY=

BUG=skia:

Review URL: https://codereview.chromium.org/806223006