Fix debugger's calculation of the context level in async code.

Fix debugger's calculation of the context level in async code.

The synthetic call to completeError has the function end as a token position.

This caused the < comparison to fail, and not find the correct context level
when creating a stacktrace in the debugger.

Fixes #28443

R=hausner@google.com

Committed: https://github.com/dart-lang/sdk/commit/3e59f95717f774f28b93634610abf24653b965f5

[Florian Schneider, 2017-01-20 23:00:42]

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

[hausner, 2017-01-20 23:28:59]

LGTM after offline discussion.

[Florian Schneider, 2017-01-21 00:08:43]

Description was changed from

==========
Fix debugger's calculation of the context level in async code.

The synthetic call to completeError has the function end as a token position.

This caused the < comparison to fail, and not find the correct context level
when creating a stacktrace in the debugger.

Fixes #28443
==========

to

==========
Fix debugger's calculation of the context level in async code.

The synthetic call to completeError has the function end as a token position.

This caused the < comparison to fail, and not find the correct context level
when creating a stacktrace in the debugger.

Fixes #28443

R=hausner@google.com

Committed:
https://github.com/dart-lang/sdk/commit/3e59f95717f774f28b93634610abf24653b965f5
==========

[Florian Schneider, 2017-01-21 00:08:44]

Committed patchset #2 (id:20001) manually as
3e59f95717f774f28b93634610abf24653b965f5 (presubmit successful).