Optimize roll operator in CPDF_PSEngine.

Optimize roll operator in CPDF_PSEngine.

Rolling 0 times is a no-op.
Rolling 0 items is a no-op.
Rolling N items J times is the same as rolling N items J % N times.
This also avoids an integer overflow corner case.

BUG=chromium:648077
Committed: https://pdfium.googlesource.com/pdfium/+/47cbc06ef6f528e4d30a869ec533d010ee79b064

[Lei Zhang, 2016-10-12 00:50:15]

The CQ bit was checked by thestig@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-12 00:50:21]

Dry run: 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 01:06:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-12 01:06:34]

Dry run: This issue passed the CQ dry run.

[Lei Zhang, 2016-10-12 01:08:00]

thestig@chromium.org changed reviewers:
+ tsepez@chromium.org

[Tom Sepez, 2016-10-12 16:04:25]

lgtm

[Lei Zhang, 2016-10-12 16:37:05]

The CQ bit was checked by thestig@chromium.org

[commit-bot: I haz the power, 2016-10-12 16:37:14]

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 16:37:30]

Description was changed from

==========
Optimize roll operator in CPDF_PSEngine.

Rolling 0 times is a no-op.
Rolling 0 items is a no-op.
Rolling N items J times is the same as rolling N items J % N times.
This also avoids an integer overflow corner case.

BUG=chromium:648077
==========

to

==========
Optimize roll operator in CPDF_PSEngine.

Rolling 0 times is a no-op.
Rolling 0 items is a no-op.
Rolling N items J times is the same as rolling N items J % N times.
This also avoids an integer overflow corner case.

BUG=chromium:648077

Committed:
https://pdfium.googlesource.com/pdfium/+/47cbc06ef6f528e4d30a869ec533d010ee79...
==========

[commit-bot: I haz the power, 2016-10-12 16:37:31]

Committed patchset #1 (id:1) as
https://pdfium.googlesource.com/pdfium/+/47cbc06ef6f528e4d30a869ec533d010ee79...