Adds source information to all values (with no detectable perf impact).  Uses Value more consistently for operations in gen.  Starts down the path of cleaning up this type.
Adds source information to all values (with no detectable perf impact).  Uses Value more consistently for operations in gen.  Starts down the path of cleaning up this type.

Review URL: http://codereview.chromium.org//8523012

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@1430 260f80e4-7a28-3924-810f-c04153c831b5

dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk