simMutex

Isolate -> Thread for tracking owner of mutex and simulator's exclusive access.

Prepares for multiple threads referencing the same isolate (in particular, the mutator and sweeper).

R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44762

[koda, 2015-03-25 23:07:37]

koda@google.com changed reviewers:
+ asiva@google.com

[koda, 2015-03-27 17:21:04]

Updated to simplify the assertion (no need to expose the type of the owner), and
internally use ThreadId, which allows moving all of OSThread to /platform
instead (it is independent of the VM).

(The simulator, OTOH, is already tied to the VM, so it makes perfect sense to
use Thread* there.)

PTAL

[siva, 2015-03-27 17:58:21]

LGTM.

As discussed offline we may at one point want an assertion to ensure that a lock
taken in one isolate is not unlocked in another isolate (the underlying thread
is the same), i.e a mutex object belongs to an isolate.

[koda, 2015-03-27 20:33:51]

Committed patchset #11 (id:200001) manually as r44762 (presubmit successful).