X87: Clean up JSConstructStub.

X87: Clean up JSConstructStub.

port 882055ff6a58f6b585575229f40f364e5f2a3ad0 (r29082).

   The original CL covers part of X87 port. This CL addes the missing changes.

original commit message:

  - fix truthfulness of comments
    - use InitializeFieldsWithFiller more consistently
    - use unsigned comparisons for pointers

    No change in functionality intended.

    Bonus: improve JavaScriptFrame::Print() for an enhanced debugging experience:

BUG=

Committed: https://crrev.com/32f32bdf12b3c856a6f4999599b359ac2203e208
Cr-Commit-Position: refs/heads/master@{#29397}

[chunyang.dai, 2015-06-30 09:12:44]

Patchset #1 (id:1) has been deleted

[chunyang.dai, 2015-06-30 09:13:04]

chunyang.dai@intel.com changed reviewers:
+ weiliang.lin@intel.com

[chunyang.dai, 2015-06-30 09:13:05]

PTAL

[Weiliang, 2015-07-01 01:24:40]

The CQ bit was checked by weiliang.lin@intel.com

[Weiliang, 2015-07-01 01:24:40]

lgtm

[commit-bot: I haz the power, 2015-07-01 01:24:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1210153007/20001

[commit-bot: I haz the power, 2015-07-01 01:52:07]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-07-01 01:52:22]

Patchset 1 (id:??) landed as
https://crrev.com/32f32bdf12b3c856a6f4999599b359ac2203e208
Cr-Commit-Position: refs/heads/master@{#29397}