Fix access semantics for foreach loops.

Fix access semantics for foreach loops.

In a statement like:

  for (x in ...) { ... }

"x" needs to be considered to be in setter context, not getter
context.

R=scheglov@google.com

Committed: https://code.google.com/p/dart/source/detail?r=41460

[Paul Berry, 2014-11-03 15:08:14]

paulberry@google.com changed reviewers:
+ scheglov@google.com

[scheglov, 2014-11-03 15:22:45]

lgtm

Would be good to update also SimpleIdentifierTest itself.

[Paul Berry, 2014-11-03 16:44:34]

On 2014/11/03 15:22:45, scheglov wrote:
> lgtm
> 
> Would be good to update also SimpleIdentifierTest itself.

Done.

[Paul Berry, 2014-11-03 16:47:36]

Committed patchset #1 (id:1) manually as 41460 (presubmit successful).