Turn ToNumberStub into a PlatformCodeStub again.

Turn ToNumberStub into a PlatformCodeStub again.

The HydrogenCodeStub is too expensive and there's no easy way to reduce
this cost, so turning it into a PlatformCodeStub solves that problem
until we can use TurboFan for code stubs.

TEST=mjsunit
R=mvstanton@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=25187

[Benedikt Meurer, 2014-11-06 11:30:40]

bmeurer@chromium.org changed reviewers:
+ mvstanton@chromium.org

[Benedikt Meurer, 2014-11-06 11:30:41]

PTAL

[Benedikt Meurer, 2014-11-06 11:35:29]

Patchset #2 (id:20001) has been deleted

[mvstanton, 2014-11-06 11:58:03]

Yep, LGTM.

[Benedikt Meurer, 2014-11-06 12:02:03]

Committed patchset #2 (id:40001) manually as 25187 (presubmit successful).