Prevent overzealous bailout due to script context.

Prevent overzealous bailout due to script context.

This is a follow-up to 2d281e71ac49 and prevents bailouts on empty
script contexts in Crankshaft, which don't need allocation. Only
non-empty script contexts should cause a bailout.

R=bmeurer@chromium.org

Committed: https://crrev.com/f3338dd3b01c95dc2b9f332efa54c99eb937c384
Cr-Commit-Position: refs/heads/master@{#27649}

[Benedikt Meurer, 2015-04-08 08:57:04]

lgtm

[Michael Starzinger, 2015-04-08 08:58:44]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-04-08 08:58:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063373003/20001

[commit-bot: I haz the power, 2015-04-08 09:00:47]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-08 09:01:03]

Patchset 2 (id:??) landed as
https://crrev.com/f3338dd3b01c95dc2b9f332efa54c99eb937c384
Cr-Commit-Position: refs/heads/master@{#27649}