Ensure unoptimized code when collecting awaiter return stack trace.

Ensure unoptimized code when collecting awaiter return stack trace.

Fixes crashes when running reload stress tests with the async stack trace stress flag
(python tools/test.py --hot-reload -t240 --builder-tag no_ipv6 language/await_exceptions_test)

R=johnmccutchan@google.com

Also: Use iterators to get function of a stack frame (refactoring only).
Committed: https://github.com/dart-lang/sdk/commit/537eacb525575b422361fcfc5692e8f1b2820850

[Florian Schneider, 2017-03-21 19:49:56]

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

[Cutch, 2017-03-21 19:51:47]

lgtm

[Florian Schneider, 2017-03-21 20:03:09]

Description was changed from

==========
Ensure unoptimized code when collecting awaiter return stack trace.

Fixes crashes when running reload stress tests with the async stack trace stress
flag
(python tools/test.py --hot-reload -t240 --builder-tag no_ipv6
language/await_exceptions_test)

Also: Use iterators to get function of a stack frame (refactoring only).
==========

to

==========
Ensure unoptimized code when collecting awaiter return stack trace.

Fixes crashes when running reload stress tests with the async stack trace stress
flag
(python tools/test.py --hot-reload -t240 --builder-tag no_ipv6
language/await_exceptions_test)

R=johnmccutchan@google.com

Also: Use iterators to get function of a stack frame (refactoring only).
Committed:
https://github.com/dart-lang/sdk/commit/537eacb525575b422361fcfc5692e8f1b2820850
==========

[Florian Schneider, 2017-03-21 20:03:11]

Committed patchset #1 (id:1) manually as
537eacb525575b422361fcfc5692e8f1b2820850 (presubmit successful).