Remove env() getter from JavaRef<>

Remove env() getter from JavaRef<>

    Due to threadsafety ambiguity, it's not generally safe to call env()
    on a random Ref you've been passed, so this removes the temptation.
    The useful LocalRef optimizations are retained though, just in that
    sub-class.

(upstreaming CL, cherrypicked cleanly)

BUG=
TEST=


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=128204

[bulach, 2012-03-02 15:41:03]

lgtm

thanks!

[joth, 2012-03-02 15:44:13]

+steveblock for renderer_host/java OWNER

[Steve Block, 2012-03-02 16:03:01]

lgtm

[joth, 2012-03-21 19:05:03]

PTAL-
Re-uploaded after re-landing the patch downstream, so this is a direct copy of
the patch already landed.
Thanks!

[Steve Block, 2012-03-21 19:42:04]

lgtm

[bulach, 2012-03-21 19:55:38]

lgtm, thanks!

[commit-bot: I haz the power, 2012-03-22 12:46:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joth@chromium.org/9584014/4001

[commit-bot: I haz the power, 2012-03-22 13:52:59]

Change committed as 128204