Oilpan: reduce visibility of Visitor::trace(const RawPtr<T>&).

Oilpan: reduce visibility of Visitor::trace(const RawPtr<T>&).

With Oilpan enabled, fail earlier and make it a compile-time error to
attempt to trace a RawPtr<>. (Previously it would only trigger an
assert at run-time.)

With Oilpan disabled, the method is needed to compile tracing methods
over RawPtr-using transition types.

R=
BUG=340522
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=167267

[sof, 2014-02-16 19:44:08]

Please take a look.

As suggested in
https://codereview.chromium.org/139803012/diff/660001/Source/heap/Visitor.h#n...

[haraken, 2014-02-17 00:50:20]

LGTM

[haraken, 2014-02-17 00:50:22]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-02-17 00:50:31]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sigbjornf@opera.com/167443003/1

[commit-bot: I haz the power, 2014-02-17 03:52:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-02-17 03:52:09]

Retried try job too often on linux_blink for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_blin...

[haraken, 2014-02-17 04:27:32]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-02-17 04:27:42]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sigbjornf@opera.com/167443003/1

[commit-bot: I haz the power, 2014-02-17 06:23:54]

Change committed as 167267