Simplify the selector map and get rid of the partial type tree.

Simplify the selector map and get rid of the partial type tree.

This new approach is a lot faster than the old approach, but we
do not use selector maps enough for this to really matter for
the overall compilation speed (yet).

There are definitely cases where having the cache has a small
positive impact and I expect that the significance of it will
increase as we start using selector maps in more places.

R=ngeoffray@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=18512

[ngeoffray, 2013-02-14 10:14:33]

LGTM

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/universe/function_set.dart
(right):

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/universe/function_set.dart:92: if
(!cache.isEmpty) cache.clear();
Why adding this?

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/universe/selector_map.dart
(right):

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/universe/selector_map.dart:18: : null;
fits in one line?

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/universe/selector_map.dart:89: } else
if (!cache.isEmpty) {
Remove this check?

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/universe/selector_map.dart:102: if
(cache != null && !cache.isEmpty) cache.clear();
Remove this check?

https://codereview.chromium.org/12262035/diff/5001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/universe/selector_map.dart:117: //
matching iterable to cut down on the overhead for cache hits.
Not sure I understand the last sentence. Looks like you're explaining why we
have a cache.