add checks needed for covariant generics, and List<E>

add checks needed for covariant generics, and fixes #154, List<E> now has the right runtime type.

R=leafp@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/fe67c032f48a734f59bce4aab19dde62221c355a

[Jennifer Messerly, 2015-04-29 23:09:06]

jmesserly@google.com changed reviewers:
+ jacobr@google.com, vsm@google.com

[vsm, 2015-04-30 14:00:51]

nice!

https://codereview.chromium.org/1117793002/diff/1/lib/runtime/dart/collection.js
File lib/runtime/dart/collection.js (right):

https://codereview.chromium.org/1117793002/diff/1/lib/runtime/dart/collection...
lib/runtime/dart/collection.js:42: dart.as(equals, dart.functionType(core.bool,
[K, K]));
We shouldn't need runtime checks on constructor params.  These are basically
static calls & should be enforced by static checks.

https://codereview.chromium.org/1117793002/diff/1/lib/src/codegen/js_codegen....
File lib/src/codegen/js_codegen.dart (right):

https://codereview.chromium.org/1117793002/diff/1/lib/src/codegen/js_codegen....
lib/src/codegen/js_codegen.dart:956: 'dart.as(#, #);', [jsParam,
_emitTypeName(paramType)]));
At some point, it'd be cleaner to hoist this before codegen.  It logically fits
with reify_coercions.

[Jennifer Messerly, 2015-05-01 20:43:04]

PTAL

https://codereview.chromium.org/1117793002/diff/1/lib/runtime/dart/collection.js
File lib/runtime/dart/collection.js (right):

https://codereview.chromium.org/1117793002/diff/1/lib/runtime/dart/collection...
lib/runtime/dart/collection.js:42: dart.as(equals, dart.functionType(core.bool,
[K, K]));
On 2015/04/30 14:00:51, vsm wrote:
> We shouldn't need runtime checks on constructor params.  These are basically
> static calls & should be enforced by static checks.

fixed

https://codereview.chromium.org/1117793002/diff/1/lib/src/codegen/js_codegen....
File lib/src/codegen/js_codegen.dart (right):

https://codereview.chromium.org/1117793002/diff/1/lib/src/codegen/js_codegen....
lib/src/codegen/js_codegen.dart:956: 'dart.as(#, #);', [jsParam,
_emitTypeName(paramType)]));
On 2015/04/30 14:00:51, vsm wrote:
> At some point, it'd be cleaner to hoist this before codegen.  It logically
fits
> with reify_coercions.

agreed, discussed offline, filed
https://github.com/dart-lang/dev_compiler/issues/161 to track

[Leaf, 2015-05-01 21:01:43]

leafp@google.com changed reviewers:
+ leafp@google.com

[Leaf, 2015-05-01 21:01:44]

lgtm

[Jennifer Messerly, 2015-05-01 21:11:56]

Committed patchset #2 (id:20001) manually as
fe67c032f48a734f59bce4aab19dde62221c355a (presubmit successful).