Add a dart2js specific HashSet implementation that follows the HashMap implementation fairly closel…

Add a dart2js specific HashSet implementation that follows the HashMap implementation fairly closely.

I'd like to wait a bit with refactoring this more aggressively until
the linked variants have landed.

R=erikcorry@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=20958

[erikcorry, 2013-04-05 08:31:06]

LGTM

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart
(right):

https://codereview.chromium.org/13715002/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
map->set

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:422:
_length++;
Last 2 lines here can go outside the "if".

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:524: var
element = JS('var', '#[#]', bucket, i);
This would be clearer if you did not reuse the name element in the method. 
Really you don't need the second one:

JS('void', '#[#] = #[#]', result, index, bucket, i)

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:604: static
_newHashTable() {
It might be better to use an array for the _numbers and _rest tables.  For V8 it
makes no difference, but that may not be true for the other VMs.

[kasperl, 2013-04-05 08:51:44]

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart
(right):

https://codereview.chromium.org/13715002/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 2013/04/05 08:31:06, erikcorry wrote:
> map->set

Done.

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:422:
_length++;
On 2013/04/05 08:31:06, erikcorry wrote:
> Last 2 lines here can go outside the "if".

Done.

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:524: var
element = JS('var', '#[#]', bucket, i);
On 2013/04/05 08:31:06, erikcorry wrote:
> This would be clearer if you did not reuse the name element in the method. 
> Really you don't need the second one:
> 
> JS('void', '#[#] = #[#]', result, index, bucket, i)

Done.

https://codereview.chromium.org/13715002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/lib/collection_patch.dart:604: static
_newHashTable() {
On 2013/04/05 08:31:06, erikcorry wrote:
> It might be better to use an array for the _numbers and _rest tables.  For V8
it
> makes no difference, but that may not be true for the other VMs.

Good point. We'll have to measure this.

[kasperl, 2013-04-05 10:23:51]

Committed patchset #2 manually as r20958 (presubmit successful).