Revert int overflow changes to ObjectPainter.

Revert int overflow changes to ObjectPainter.

Partial revert of http://crrev.com/2404583002 (keeping the divide-by-zero change
in Color). We don't consider these int overflow safeguards to be necessary in
this part of the code, per offline discussion with ubsan fuzzer folk and an
appropriate selection of Blink eng with fuzzing historical background.

BUG=652589
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/f29fc457dc4b6663998a40958f782bfbb89d6dc0
Cr-Commit-Position: refs/heads/master@{#424620}

[wkorman, 2016-10-11 23:06:37]

Description was changed from

==========
Revert int overflow changes to ObjectPainter.

Partial revert of http://crrev.com/2404583002 (keeping the divide-by-zero change
in Color). We don't consider these int overflow safeguards to be necessary in
this part of the code, per offline discussion with ubsan fuzzer folk and an
appropriate selection of Blink eng with fuzzing historical background.

BUG=652589
==========

to

==========
Revert int overflow changes to ObjectPainter.

Partial revert of http://crrev.com/2404583002 (keeping the divide-by-zero change
in Color). We don't consider these int overflow safeguards to be necessary in
this part of the code, per offline discussion with ubsan fuzzer folk and an
appropriate selection of Blink eng with fuzzing historical background.

BUG=652589
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[wkorman, 2016-10-11 23:07:05]

wkorman@chromium.org changed reviewers:
+ eae@chromium.org, pdr@chromium.org

[pdr., 2016-10-11 23:15:10]

On 2016/10/11 at 23:07:06, wkorman wrote:
> 

LGTM. Sorry for the churn, partially my fault :/

[eae, 2016-10-11 23:17:20]

LGTM

[wkorman, 2016-10-11 23:19:39]

The CQ bit was checked by wkorman@chromium.org

[commit-bot: I haz the power, 2016-10-11 23:20:16]

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, 2016-10-12 00:52:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-12 00:56:00]

Description was changed from

==========
Revert int overflow changes to ObjectPainter.

Partial revert of http://crrev.com/2404583002 (keeping the divide-by-zero change
in Color). We don't consider these int overflow safeguards to be necessary in
this part of the code, per offline discussion with ubsan fuzzer folk and an
appropriate selection of Blink eng with fuzzing historical background.

BUG=652589
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Revert int overflow changes to ObjectPainter.

Partial revert of http://crrev.com/2404583002 (keeping the divide-by-zero change
in Color). We don't consider these int overflow safeguards to be necessary in
this part of the code, per offline discussion with ubsan fuzzer folk and an
appropriate selection of Blink eng with fuzzing historical background.

BUG=652589
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/f29fc457dc4b6663998a40958f782bfbb89d6dc0
Cr-Commit-Position: refs/heads/master@{#424620}
==========

[commit-bot: I haz the power, 2016-10-12 00:56:01]

Patchset 1 (id:??) landed as
https://crrev.com/f29fc457dc4b6663998a40958f782bfbb89d6dc0
Cr-Commit-Position: refs/heads/master@{#424620}

[Timothy Loh, 2016-10-12 05:30:18]

I've seen a few of these ubsan integer overflow bugs pop up, could you document
somewhere what you've learned from your offline discussions so everyone else can
also know how to appropriately handle these? Thanks!