Reland of Implement canComputeFastBounds() for image filters.

Reland of Implement canComputeFastBounds() for image filters. (patchset #1 id:1 of https://codereview.chromium.org/1300403003/ )

Reason for revert:
The Mac compile issue was fixed here: https://chromium.googlesource.com/chromium/src/+/fdd331a42ae0b9a6909a121020735161ab61c6e5

Original issue's description:
> Revert of Implement canComputeFastBounds() for image filters. (patchset #8 id:130001 of https://codereview.chromium.org/1296943002/ )
> 
> Reason for revert:
> This causes a syntax error.
> 
> http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_compile_dbg_ng/builds/87819/steps/compile%20%28with%20patch%29/logs/stdio
> 
> Original issue's description:
> > Implement canComputeFastBounds() for image filters.
> > 
> > Image filters have never implemented this check, which means that
> > filters which affect transparent black falsely claim they can compute
> > their bounds.
> > 
> > Implemented an affectsTransparentBlack() virtual for image 
> > filters, and a similar helper function for color filters.
> > 
> > This will affect the following GMs: imagefiltersscaled 
> > (lighting, perlin noise now filter to clip), 
> > colorfilterimagefilter (new test case), imagefiltersclipped 
> > (perlin noise now filters to clip).
> > 
> > Note: I de-inlined SkPaint::canComputeFastBounds() to avoid adding
> > a dependency from SkPaint.h to SkImageFilter.h.h. Skia benches show
> > no impact from this change, but will watch the perf bots carefully.
> > 
> > BUG=4212
> > 
> > Committed: https://skia.googlesource.com/skia/+/915881fe743f9a789037695f543bc6ea189cd0cb
> 
> TBR=reed@google.com,senorblanco@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=4212
> 
> Committed: https://skia.googlesource.com/skia/+/12d8472d31ea5edb636d7d5214db253570115c40

TBR=reed@google.com,herb@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=4212
Committed: https://skia.googlesource.com/skia/+/0abdf766d395ed3b7059511425f431589eca05f6

[Stephen White, 2015-08-20 18:10:21]

Created Reland of Implement canComputeFastBounds() for image filters.

[commit-bot: I haz the power, 2015-08-20 18:10:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1301823005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1301823005/1

[commit-bot: I haz the power, 2015-08-20 18:10:44]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/0abdf766d395ed3b7059511425f431589eca05f6