Don’t search scope of top-level class twice

Don’t search scope of top-level class twice

When resolving an identifier in top-level code, we don’t need
to search the class scope. That scope is searched again when
resolving the identifier in the library scope.

Sadly, the change makes no measurable difference. It’s just a drop
in the bucket.

R=regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45249

[hausner, 2015-04-17 17:17:01]

hausner@google.com changed reviewers:
+ regis@google.com

[regis, 2015-04-17 17:19:42]

lgtm

[hausner, 2015-04-17 18:08:16]

Committed patchset #1 (id:1) manually as r45249 (presubmit successful).