dart2js: accept const map literals as expression statements.

dart2js: accept const map literals as expression statements.

Dart2js was broken for:

    <String, int> {};

The reason was that we tried to find an identifier after an initial type (looking for something like `Set<int> foo`) to parse a declaration. We assumed that the first token would be a type name and skipped the `<` when we did this search, thus believing that there was a declaration.

BUG= http://dartbug.com/12793
BUG= http://dartbug.com/12794
BUG= http://dartbug.com/21155
R=ahe@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42356

[floitsch, 2014-12-12 14:25:05]

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

[ahe, 2014-12-12 14:32:42]

Minor issue: fix is correct, but in the wrong method. No problems otherwise.

https://codereview.chromium.org/796363003/diff/1/pkg/compiler/lib/src/scanner...
File pkg/compiler/lib/src/scanner/parser.dart (left):

https://codereview.chromium.org/796363003/diff/1/pkg/compiler/lib/src/scanner...
pkg/compiler/lib/src/scanner/parser.dart:1634: Token identifier =
peekIdentifierAfterOptionalType(token.next);
peekIdentifierAfterOptionalType is only called once, so it should be handling
this case.

[floitsch, 2014-12-12 14:38:47]

Knowing that peekIdentifierAfterOptionalType is only called once simplifies the
fix.

PTAL.

https://codereview.chromium.org/796363003/diff/1/pkg/compiler/lib/src/scanner...
File pkg/compiler/lib/src/scanner/parser.dart (left):

https://codereview.chromium.org/796363003/diff/1/pkg/compiler/lib/src/scanner...
pkg/compiler/lib/src/scanner/parser.dart:1634: Token identifier =
peekIdentifierAfterOptionalType(token.next);
On 2014/12/12 14:32:41, ahe wrote:
> peekIdentifierAfterOptionalType is only called once, so it should be handling
> this case.

Done.

[ahe, 2014-12-12 17:22:40]

lgtm

[floitsch, 2014-12-13 17:13:06]

Committed patchset #2 (id:20001) manually as 42356 (presubmit successful).