qualified return type breaks DartC parser.

[floitschG]

We have (now had) the following code in our leg-compiler:
===

library("io");

import('../../lang.dart', prefix: 'frog');

...
frog.SourceFile readSync(String fileName) {
  return new frog.SourceFile(fileName, frog.world.files.readAll(fileName));
}
===
http://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/frog/leg/io/io.dart?spec=svn1359&r=1359

DartC parser can't handle the qualified return-type and aborts. Even worse (from the Editor's perspective) is that it doesn't continue on new files, thus disabling warnings, errors and code-completion in the editor.

[DartBot]

This comment was originally written by [email protected]

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Set owner to @scheglov.

[scheglov]

http://codereview.chromium.org/8662019/

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Added Fixed label.