Cleanup timeline stream enabled flag so that it can be easily tested from an intrinsic

Cleanup timeline stream enabled flag so that it can be easily tested from an intrinsic

- Drop no-longer used globally enabled stream flags. This leaves just one source of truth.
- Kill 'Enabled()' for 'enabled()'.
- Store pointer to Timeline::DartStream in Thread.
- Store enabled as an uintptr_t instead of a bool to make it easier for generated code to access.

R=rmacnak@google.com

Committed: https://github.com/dart-lang/sdk/commit/d1d3ba587b0f177bf68eb5078e83de185ff3e57d

[Cutch, 2016-05-13 21:25:38]

Description was changed from

==========
Cleanup timeline stream enabled flag so that it can be easily tested from an
intrinsic

BUG=
==========

to

==========
Cleanup timeline stream enabled flag so that it can be easily tested from an
intrinsic

- Drop no-longer used globally enabled stream flags. This leaves just one source
of truth.
- Kill 'Enabled()' for 'enabled()'.
- Store pointer to Timeline::DartStream in Thread.
- Store enabled as an uintptr_t instead of a bool to make it easier for
generated code to access.
==========

[Cutch, 2016-05-13 21:25:38]

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

[rmacnak, 2016-05-16 17:07:15]

lgtm

[Cutch, 2016-05-16 17:30:53]

Description was changed from

==========
Cleanup timeline stream enabled flag so that it can be easily tested from an
intrinsic

- Drop no-longer used globally enabled stream flags. This leaves just one source
of truth.
- Kill 'Enabled()' for 'enabled()'.
- Store pointer to Timeline::DartStream in Thread.
- Store enabled as an uintptr_t instead of a bool to make it easier for
generated code to access.
==========

to

==========
Cleanup timeline stream enabled flag so that it can be easily tested from an
intrinsic

- Drop no-longer used globally enabled stream flags. This leaves just one source
of truth.
- Kill 'Enabled()' for 'enabled()'.
- Store pointer to Timeline::DartStream in Thread.
- Store enabled as an uintptr_t instead of a bool to make it easier for
generated code to access.

R=rmacnak@google.com

Committed:
https://github.com/dart-lang/sdk/commit/d1d3ba587b0f177bf68eb5078e83de185ff3e57d
==========

[Cutch, 2016-05-16 17:30:54]

Committed patchset #1 (id:1) manually as
d1d3ba587b0f177bf68eb5078e83de185ff3e57d (presubmit successful).