Allow `return;` in async method.

Allow `return;` in async method.

BUG=http://dartbug.com/23200
R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/083dce756bf4c9fdebe89e0338c504665e7eac6f

[Johnni Winther, 2015-05-22 13:53:17]

johnniwinther@google.com changed reviewers:
+ floitsch@google.com

[kevmoo, 2015-05-22 14:49:13]

On 2015/05/22 13:53:18, Johnni Winther wrote:

DBC: is there a shared test that will cover warnings/errors in
analyzer/vm/dart2js that can cover this case, too?

[floitsch, 2015-05-22 19:03:57]

LGTM.

[Johnni Winther, 2015-05-25 10:46:22]

On 2015/05/22 14:49:13, kevmoo wrote:
> On 2015/05/22 13:53:18, Johnni Winther wrote:
> 
> DBC: is there a shared test that will cover warnings/errors in
> analyzer/vm/dart2js that can cover this case, too?

For error we already do, for warnings we can't/don't:

`can't`: The VM doesn't produce warnings.

`don't`: Currently there is no way for the bot to test warnings from dart2js.
Otherwise the language tests and co19 tests could be used, like we currently do
for the analyzer.

[Johnni Winther, 2015-05-25 11:07:29]

Committed patchset #1 (id:1) manually as
083dce756bf4c9fdebe89e0338c504665e7eac6f (presubmit successful).