Update color emoji GMs after https://codereview.chromium.org/759613005/.

TBR=halcanary@google.com

Review URL: https://codereview.chromium.org/775163002
rebaseline images

TBR=

Review URL: https://codereview.chromium.org/776983003
Add XferProcessor factory in GrPaint and GrDrawState.

In this CL the XP should have zero effect on the actual rendering pipeline.

BUG=skia:

Review URL: https://codereview.chromium.org/751283002
Revert of remove unused device::eraseColor (patchset #1 id:1 of https://codereview.chromium.org/765643004/)

Reason for revert:
../../skia/ext/bitmap_platform_device_cairo.cc:131:13: error: no member named 'eraseColor' in 'skia::BitmapPlatformDevice'

Original issue's description:
> remove unused device::eraseColor
>
> BUG=skia:
> TBR=
>
> Committed: https://skia.googlesource.com/skia/+/b1ab276c3719d6690e58f347c25126d2b8929c5d

TBR=reed@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/777003002
Add glGetShaderPrecisionFormat

Review URL: https://codereview.chromium.org/778703003
Fix PdfViewer BGR byte order

BUG=skia:3184

Review URL: https://codereview.chromium.org/775763003
Copy src in SkDrawLooper::computeFastBounds().

We do alias src and dst when building the BBH.  This meant we calculated
the wrong bounds in LayoutTests/ietestcenter/css3/text/textshadow-010.htm.

Not sure how best to test this inside Skia.  It may become moot after I
work through the API changes we were talking about today, but if not I'll
make sure it's tested somehow before I'm done with SkDrawLoopers.

BUG=skia:3186

Review URL: https://codereview.chromium.org/760023004
Use static XPF for porter duff xp factories.

BUG=skia:

Review URL: https://codereview.chromium.org/776843004