Enable iterating over roots from helper threads by moving stack walking.

Enable iterating over roots from helper threads by moving stack walking.

This will be needed for helper threads to invoke GC.

BUG=
R=johnmccutchan@google.com

Committed: https://github.com/dart-lang/sdk/commit/faaf60801f72d7397cb6a87f54f2470e69a9a427

[koda, 2015-08-11 16:04:41]

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

[Cutch, 2015-08-11 16:07:13]

lgtm

[koda, 2015-08-11 16:41:10]

Committed patchset #1 (id:1) manually as
faaf60801f72d7397cb6a87f54f2470e69a9a427 (presubmit successful).

[Ivan Posva, 2015-08-11 17:41:31]

iposva@google.com changed reviewers:
+ iposva@google.com

[Ivan Posva, 2015-08-11 17:41:31]

Please fix.

-Ivan

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/isolate.cc
File runtime/vm/isolate.cc (left):

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/isolate.cc#oldco...
runtime/vm/isolate.cc:1602: StackFrameIterator frames_iterator(validate_frames);
Can you please explain how we are validating frames after this change?

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/thread_registry.h
File runtime/vm/thread_registry.h (right):

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/thread_registry....
runtime/vm/thread_registry.h:130: StackFrameIterator frames_iterator(efi,
false);
Please do not use explicit constants and use the appropriately named constant
StackFrameIterator::kDontValidateFrames.

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/thread_test.cc
File runtime/vm/thread_test.cc (right):

https://codereview.chromium.org/1282423003/diff/1/runtime/vm/thread_test.cc#n...
runtime/vm/thread_test.cc:138: /* validate_frames = */ true);
ditto