Recognize unmodifiable lists

Recognize unmodifiable lists

Add a new type, JSUnmodifiableArray, that is the type returned by
List.unmodifiable and the type of const list literals.

R=floitsch@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45575

[sra1, 2015-05-06 02:24:30]

Patchset #1 (id:1) has been deleted

[sra1, 2015-05-06 02:29:40]

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

[sra1, 2015-05-06 02:29:40]

Fix for http://dartbug.com/23309

We could do better with various unions of fixed length iterables.  I had started
along that path but it turns out we needed a lot more extra types so I just went
with the simplest approach.

[floitsch, 2015-05-06 06:28:32]

LGTM.

https://codereview.chromium.org/1126063002/diff/20001/pkg/compiler/lib/src/ss...
File pkg/compiler/lib/src/ssa/optimize.dart (right):

https://codereview.chromium.org/1126063002/diff/20001/pkg/compiler/lib/src/ss...
pkg/compiler/lib/src/ssa/optimize.dart:102: bool isFixedLength(mask, Compiler
compiler) {
Add comment in which direction this function is conservative.
Will it rather say too often it is fixed or the other way round?

[sra1, 2015-05-06 21:25:36]

Committed patchset #2 (id:40001) manually as 45575 (presubmit successful).