Do not iterate past the end on processing leaf class.

Do not iterate past the end on processing leaf class.

When checking that the leftmost class of a GC-derived class has the
expected shape, take care not step past the end of the leftmost class'
own base classes, i.e., when processing A in

  class A { };
  class B : public A, ...some GC base... { };

R=haraken
BUG=446580
Committed: https://crrev.com/ab26c4a28236793c15d9daa7cff89173be4cb527
Cr-Commit-Position: refs/heads/master@{#310253}

[sof, 2015-01-06 21:07:38]

sigbjornf@opera.com changed reviewers:
+ oilpan-reviews@chromium.org

[sof, 2015-01-06 21:07:38]

Please take a look.

[haraken, 2015-01-07 01:34:55]

LGTM

[sof, 2015-01-07 08:11:39]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-01-07 08:12:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/840623002/1

[commit-bot: I haz the power, 2015-01-07 08:54:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-07 08:55:56]

Patchset 1 (id:??) landed as
https://crrev.com/ab26c4a28236793c15d9daa7cff89173be4cb527
Cr-Commit-Position: refs/heads/master@{#310253}