Blink GC plugin: Don't check conditions on invalid compilation units.

Blink GC plugin: Don't check conditions on invalid compilation units.

BUG=421958, 334149
R=hans@chromium.org, haraken@chromium.org

Committed: https://crrev.com/1ce6049f0a6f3a1bc989b5019564bb42cc47f1b4
Cr-Commit-Position: refs/heads/master@{#299084}

[zerny-google, 2014-10-10 08:42:00]

Hi Hans and Haraken,

This CL should address crbug.com/421958
However, I can't get my local chromium/clang build working ATM. If one of you
could verify the regression test fails/passes without/with the fix feel free to
add this to the commit queue. If you are out of time I'll pick this up again
after I'm back from vacation (Oct 20).

[haraken, 2014-10-10 08:55:02]

LGTM

I'll land this.

[haraken, 2014-10-10 08:55:05]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-10-10 08:55:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/641353002/1

[commit-bot: I haz the power, 2014-10-10 09:32:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-10 09:33:45]

Patchset 1 (id:??) landed as
https://crrev.com/1ce6049f0a6f3a1bc989b5019564bb42cc47f1b4
Cr-Commit-Position: refs/heads/master@{#299084}