Revert of Matrix convolution bounds fix; affectsTransparentBlack fixes. (patchset #4 id:60001 of https://codereview.chromium.org/1500923004/ )

Reason for revert:
Introduced memory leak; pixel changes in Chrome.

Original issue's description:
> Matrix convolution bounds fix; affectsTransparentBlack fixes.
>
> Because the convolution kernel is (currently) applied in device space,
> there's no way to know which object-space pixels will be touched. So
> return false from canComputeFastBounds().
>
> The results from the matrixconvolution GM were actually wrong, since
> they were showing edge differences on the clip boundaries, where they
> should really only show on crop boundaries. I added a crop to the GM
> to keep the results the same (which are useful to test the different
> convolution tile modes).
>
> While I was at it, SkImageFilter::affectsTransparentBlack() was
> inapplicable on most things except color filters, and its use on
> leaf nodes was confusing. So I removed it, and made
> SkImageFilter::canComputeFastBounds() virtual instead.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/8705ec80518ef551994b82ca5ccaeb0241d6adec

TBR=reed@google.com,reed@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1497083005
10 files changed