Allow `return <expr>` in sync* and async* javascript.

Allow `return <expr>` in sync* and async* javascript.


BUG=
R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/a466b6bd39bc1de797428abd9103797d1894c7c9

[sigurdm, 2015-07-15 12:26:02]

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

[floitsch, 2015-07-15 14:03:16]

LGTM.
Please get the real Dart code (that triggered this) and add it as async test
too.

https://codereview.chromium.org/1235793006/diff/1/pkg/compiler/lib/src/js/rew...
File pkg/compiler/lib/src/js/rewrite_async.dart (right):

https://codereview.chromium.org/1235793006/diff/1/pkg/compiler/lib/src/js/rew...
pkg/compiler/lib/src/js/rewrite_async.dart:1289: // It is interpreted as `expr;
return;`
Add more comment of why this could ever be legal. (I.e. we know that the 'expr'
throws, and the return is just to tell V8 that the code won't continue here).

[sigurdm, 2015-07-15 14:44:47]

PTAL at the test.

[floitsch, 2015-07-15 14:55:00]

LGTM.

https://codereview.chromium.org/1235793006/diff/20001/tests/language/syncstar...
File tests/language/syncstar_less_than_test.dart (right):

https://codereview.chromium.org/1235793006/diff/20001/tests/language/syncstar...
tests/language/syncstar_less_than_test.dart:7: confuse(x) => [1, 'x', true,
null, x].last;
The expect package has annotations to assume 'dynamic' for return types.
'.last' on a list-literal is way too easy to optimize.

[floitsch, 2015-07-15 14:57:24]

On 2015/07/15 14:55:00, floitsch wrote:
> LGTM.
> 
>
https://codereview.chromium.org/1235793006/diff/20001/tests/language/syncstar...
> File tests/language/syncstar_less_than_test.dart (right):
> 
>
https://codereview.chromium.org/1235793006/diff/20001/tests/language/syncstar...
> tests/language/syncstar_less_than_test.dart:7: confuse(x) => [1, 'x', true,
> null, x].last;
> The expect package has annotations to assume 'dynamic' for return types.
> '.last' on a list-literal is way too easy to optimize.

I'm landing this CL now (since it unbreaks the build). Please do a follow-up CL
for the test.

[floitsch, 2015-07-15 14:59:10]

Committed patchset #2 (id:20001) manually as
a466b6bd39bc1de797428abd9103797d1894c7c9 (presubmit successful).

[sigurdm, 2015-07-20 07:18:37]

LGTM