Delete IterableMixinWorkaround

Delete IterableMixinWorkaround

Most code in IterableMixinWorkaround was unused.  The remaining O(20)
methods have been moved to their only use on JSArray.

I looked into using ListMixin on JSArray.  The code was clearly worse
- nearly 1% bloat on swarm and some less precise inference.  I think
it is reasonable to have the JSArray methods special-cased for
performance reasons.

R=lrn@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44006

[sra1, 2015-02-24 04:04:52]

sra@google.com changed reviewers:
+ lrn@google.com

[sra1, 2015-02-24 04:04:53]

https://codereview.chromium.org/931283006/diff/1/pkg/compiler/lib/src/js_back...
File pkg/compiler/lib/src/js_backend/backend.dart (left):

https://codereview.chromium.org/931283006/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/backend.dart:91: 'IterableMixinWorkaround':
const <String>['forEach'],
We should possibly remove this hack entirely.
If we want the feature, annotations would be a better way to go.

[Lasse Reichstein Nielsen, 2015-02-24 12:34:24]

LGTM!!!
Still duplicates some functionality of ListBase which would be better reused
(but I see some functions are optimized). Definitely better than having it
duplicated in IterableMixinWorkaround.

[sra1, 2015-02-24 22:57:35]

Committed patchset #1 (id:1) manually as 44006 (presubmit successful).