ES6 computed property names

This adds support for computed property names, under the flag
--harmony-computed-property-names, for both object literals and
classes.

This is a revert of the revert, a76419f0f497db156eb1010e9b4be398951280cb.

This changes to do an early bailout in
HOptimizedGraphBuilder::VisitObjectLiteral instead of doing that in the later
loop.

BUG=v8:3754
LOG=Y
TBR=dslomov@chromium.org

Review URL: https://codereview.chromium.org/792233008

Cr-Commit-Position: refs/heads/master@{#25868}
Whitespace change to trigger bots.

Cr-Commit-Position: refs/heads/master@{#25869}
Whitespace change to trigger bots.

Cr-Commit-Position: refs/heads/master@{#25870}
Whitespace change to trigger bots.

Cr-Commit-Position: refs/heads/master@{#25871}
Revert of ES6 computed property names (patchset #1 id:1 of https://codereview.chromium.org/792233008/)

Reason for revert:
[sheriff] Still crashes on win32 (XP):
http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%201/builds/1380

Original issue's description:
> ES6 computed property names
>
> This adds support for computed property names, under the flag
> --harmony-computed-property-names, for both object literals and
> classes.
>
> This is a revert of the revert, a76419f0f497db156eb1010e9b4be398951280cb.
>
> This changes to do an early bailout in
> HOptimizedGraphBuilder::VisitObjectLiteral instead of doing that in the later
> loop.
>
> BUG=v8:3754
> LOG=Y
> TBR=dslomov@chromium.org

TBR=dslomov@chromium.org,arv@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=v8:3754

Review URL: https://codereview.chromium.org/811593004

Cr-Commit-Position: refs/heads/master@{#25872}