VM "cherry-picks" to fix memory leaks in 1.12:

VM "cherry-picks" to fix memory leaks in 1.12:

This is merged into 1.12.0-dev.5.9


Cherry-picks and associated conflict resolution for:
664742f0162a13e0d60c65de0a713df8acd7d8e9
d0b03eebbd63261e7beb8413aa9ce9dfa2a862cc
3aa62d03fcbffc2f2a77f05d2c8e975b75a56d76
74e02785b0e534e469668ce2cabced7d26ec55b1
028c9952959be3b1f275c3cfbe805ab80c49f07a

=====

Keep StoreBuffer::global_mutex_ and global_empty_ alive.

At Dart::CleanUp time, there may still be threads around that access their store buffer, so we need to keep these around until @zanderso lands the clean shutdown CL.

We should stop leaking them once we cleanly stop all threads at VM shutdown (see issue 23844).

BUG=https://github.com/dart-lang/sdk/issues/24169
R=iposva@google.com

Review URL: https://codereview.chromium.org//1305123003 .

Conflicts:
	runtime/vm/dart.cc

Fix reuse of free store buffer blocks from the global cache of free blocks.

Add StoreBuffer::ShutDown to delete global cache of free blocks on VM shutdown.

BUG=https://github.com/dart-lang/sdk/issues/24129
R=iposva@google.com

Review URL: https://codereview.chromium.org//1309603003 .

Conflicts:
	runtime/vm/dart.cc

- Prevent interrupting the NULL thread when the isolate is   exiting from within a thread.

BUG=

Review URL: https://codereview.chromium.org//1307833002 .

- Initialize fields used in the profiler interrupts.

BUG=
R=koda@google.com

Review URL: https://codereview.chromium.org//1304043003 .

Completely remove InterruptableThreadState

- InterruptableThreadState is gone.
- Moved InterruptableThreadState fields directly into Thread.
- Iterate over all threads in an isolate when profiling.
- Still only sample the mutator thread.

Fix ThreadRegistry leak

- When deleting a Thread, iterate over all isolates and remove it from the isolate's thread registry.

R=iposva@google.com

Review URL: https://codereview.chromium.org//1293253005 .

Conflicts:
	runtime/vm/isolate.h
	runtime/vm/thread.cc
	runtime/vm/thread.h
	runtime/vm/thread_interrupter.cc
	runtime/vm/thread_interrupter_android.cc
	runtime/vm/thread_interrupter_linux.cc
	runtime/vm/thread_interrupter_macos.cc

- Fix leak in TimelineEventRecorder.
- Fix leak in ThreadRegistry.

[Ivan Posva, 2015-08-21 23:54:52]

iposva@google.com changed reviewers:
+ johnmccutchan@google.com, mit@google.com, whesse@google.com
- iposva@google.com

[Ivan Posva, 2015-08-22 00:07:33]

Related to integration request at https://github.com/dart-lang/sdk/issues/24177

-Ivan