Move feConvolveMatrix error handling to FEConvolveMatrix

Move feConvolveMatrix error handling to FEConvolveMatrix

This moves the checking of error-conditions from
SVGFEConvolveMatrixElement::build to SkImageFilter build time
(FEConvolveMatrix::createImageFilter), with the change in behavior that
an feConvolveMatrix primitive that is "in error" now produces
transparent black rather than fail the chain (for 'filter' - is ignored
for '-webkit-filter'). This new behavior matches Gecko.
The 'order' vs. size('kernelMatrix') checking is also strengthed / made
more obvious by explicitly failing when overflowing the (positive) int
range. (And avoids depending on signed overflow.)
Also introduce a helper FilterEffect::createTransparentBlack and use in
FEConvolveMatrix and FEImage, and drop a bunch of unused accessor
methods on FEConvolveMatrix.

BUG=533457
Committed: https://crrev.com/a5c80d87788a2aec8c82ba24345aae731e1d2c71
Cr-Commit-Position: refs/heads/master@{#351139}

[fs, 2015-09-28 13:54:54]

fs@opera.com changed reviewers:
+ fmalita@chromium.org, pdr@chromium.org, senorblanco@chromium.org

[Stephen White, 2015-09-28 14:03:29]

LGTM

I like the createTransparentBlack() change. +1 for self-documenting code.

[fs, 2015-09-28 19:49:49]

The CQ bit was checked by fs@opera.com

[commit-bot: I haz the power, 2015-09-28 19:50:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1376473002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1376473002/1

[commit-bot: I haz the power, 2015-09-28 20:56:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-28 20:58:48]

Patchset 1 (id:??) landed as
https://crrev.com/a5c80d87788a2aec8c82ba24345aae731e1d2c71
Cr-Commit-Position: refs/heads/master@{#351139}