Produce cached data only for scripts which compile without errors.

Produce cached data only for scripts which compile without errors.

ScriptCompiler::CompileUnbound handles cached data only when there was no
compilation error, so, if we produce the data for erroneous scripts, the
ScriptData object is leaked.

In addition, producing cached data for erroneous scripts makes little sense.

R=ulan@chromium.org
BUG=370327
LOG=N

Committed: https://code.google.com/p/v8/source/detail?r=21164

[marja, 2014-05-06 08:30:25]

ulan, ptal

[ulan, 2014-05-06 08:31:08]

lgtm

[marja, 2014-05-06 11:23:03]

Committed patchset #1 manually as r21164 (presubmit successful).