Add check for duplicate field initialization

Add check for duplicate field initialization

This change adds a check that reports duplicate initialization
of instance fields. Fixes issues 921 and 1034.

There were several tests in the language suite that had duplicate
initializers for final instance fields. Corrected the tests.

dart2js also contained duplicate initializations of a couple
of final fields.
Committed: https://code.google.com/p/dart/source/detail?r=10146

[regis, 2012-08-01 21:58:03]

LGTM, but you should add at least one negative test verifying that duplicate
field initialization is reported. Since negative tests are now discouraged, you
should use the "/// 01:" notation in one or more of the modified tests.

http://codereview.chromium.org/10825140/diff/1/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

http://codereview.chromium.org/10825140/diff/1/runtime/vm/parser.cc#newcode1720
runtime/vm/parser.cc:1720: "Duplicate initialization for field %s",
Most error messages start with a lower case.

[hausner, 2012-08-01 22:23:14]

Thanks for the review. We have several negative tests in co19. They now all
pass, which is why I removed them from the status file.

http://codereview.chromium.org/10825140/diff/1/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

http://codereview.chromium.org/10825140/diff/1/runtime/vm/parser.cc#newcode1720
runtime/vm/parser.cc:1720: "Duplicate initialization for field %s",
On 2012/08/01 21:58:03, regis wrote:
> Most error messages start with a lower case.

Done.

[ahe, 2012-08-02 17:10:35]

Hi Matthias,

Thank you for fixing the bug in dart2js!

Cheers,
Peter