check for zero scale in SkDraw::ComputeResScaleForStroking

check for zero scale in SkDraw::ComputeResScaleForStroking

If the transform used to compute the res scale has both 0 scale and skew,
then it will currently compute a 0 res scale. This causes getFillPath
to trigger an assertion while using SkStroke since that can't handle
a 0 res scale.

Downstream Firefox bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1284356

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2125933003

Committed: https://skia.googlesource.com/skia/+/a4b8704e76cb2136a3ff8c1553690f30b96870e0

[lsalzman1, 2016-07-06 18:17:13]

Description was changed from

==========
check for zero scale in SkDraw::ComputeResScaleForStroking

If the transform used to compute the res scale has both 0 scale and skew,
then it will currently compute a 0 res scale. This causes getFillPath
to trigger an assertion while using SkStroke since that can't handle
a 0 res scale.

Downstream Firefox bug report:
https://bugzilla.mozilla.org/show_bug.cgi?id=1284356

BUG=skia:
==========

to

==========
check for zero scale in SkDraw::ComputeResScaleForStroking

If the transform used to compute the res scale has both 0 scale and skew,
then it will currently compute a 0 res scale. This causes getFillPath
to trigger an assertion while using SkStroke since that can't handle
a 0 res scale.

Downstream Firefox bug report:
https://bugzilla.mozilla.org/show_bug.cgi?id=1284356

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2125933003
==========

[lsalzman1, 2016-07-06 18:17:45]

lsalzman@mozilla.com changed reviewers:
+ caryclark@google.com

[caryclark, 2016-07-06 18:53:03]

lgtm

[lsalzman1, 2016-07-06 18:53:52]

The CQ bit was checked by lsalzman@mozilla.com

[commit-bot: I haz the power, 2016-07-06 18:54:02]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-06 19:19:58]

Description was changed from

==========
check for zero scale in SkDraw::ComputeResScaleForStroking

If the transform used to compute the res scale has both 0 scale and skew,
then it will currently compute a 0 res scale. This causes getFillPath
to trigger an assertion while using SkStroke since that can't handle
a 0 res scale.

Downstream Firefox bug report:
https://bugzilla.mozilla.org/show_bug.cgi?id=1284356

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2125933003
==========

to

==========
check for zero scale in SkDraw::ComputeResScaleForStroking

If the transform used to compute the res scale has both 0 scale and skew,
then it will currently compute a 0 res scale. This causes getFillPath
to trigger an assertion while using SkStroke since that can't handle
a 0 res scale.

Downstream Firefox bug report:
https://bugzilla.mozilla.org/show_bug.cgi?id=1284356

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2125933003

Committed:
https://skia.googlesource.com/skia/+/a4b8704e76cb2136a3ff8c1553690f30b96870e0
==========

[commit-bot: I haz the power, 2016-07-06 19:19:59]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/a4b8704e76cb2136a3ff8c1553690f30b96870e0