Add JS implementation of LinkedHashMap.

Add JS implementation of LinkedHashMap.

R=erikcorry@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=21072

[erikcorry, 2013-04-08 13:15:52]

LGTM

As discussed offline there is an opportunity for refactoring to avoid code
duplication once all 4 implementations are in.

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart
(right):

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:362: // The
hash map contents is divided into three parts: one part for
is -> are

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:522: void
_addHashTableEntry(var table, K key, V value) {
I find it rather painful to consider that we are doing the lookup twice here. 
Doing a _getTableEntry immediately and testing for null must be faster.

[kasperl, 2013-04-08 13:31:13]

Thanks for the review. Looking forward to getting started on the refactoring.

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart
(right):

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:362: // The
hash map contents is divided into three parts: one part for
On 2013/04/08 13:15:52, erikcorry wrote:
> is -> are

Done.

https://codereview.chromium.org/13599005/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:522: void
_addHashTableEntry(var table, K key, V value) {
On 2013/04/08 13:15:52, erikcorry wrote:
> I find it rather painful to consider that we are doing the lookup twice here. 
> Doing a _getTableEntry immediately and testing for null must be faster.

Done.

[kasperl, 2013-04-08 13:51:21]

Committed patchset #3 manually as r21072 (presubmit successful).