Add TypeMirror.isSubtypeOf, TypeMirror.isAssignableTo, ClassMirror.isSubclassOf

Add TypeMirror.isSubtypeOf, TypeMirror.isAssignableTo, ClassMirror.isSubclassOf to the API, the VM runtime mirrors and the source mirrors.

BUG=http://dartbug.com/12439
BUG=http://dartbug.com/13856
R=gbracha@google.com, johnniwinther@google.com, regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32577

[rmacnak, 2014-01-08 03:02:43]

The tests are quite deficient

[gbracha, 2014-01-08 19:30:46]

Tests lgtm but we need more. In particular, tests for function types and
typedefs.

[rmacnak, 2014-01-11 00:14:33]

+regis for vm implementation

[rmacnak, 2014-01-11 00:14:56]

Added tests for typedefs, function types, type variables, dynamic and void.

[gbracha, 2014-01-11 01:53:30]

See comments on tests. Dynamic is a subtype of anything and we are missing some
cases (a few of which are really worth checking).

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
File tests/lib/mirrors/relation_assignable_test.dart (right):

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
tests/lib/mirrors/relation_assignable_test.dart:82:
Expect.isTrue(DubPred.isAssignableTo(Obj));
I hesitate to suggest more cases, but the reverse is also true:
Obj.isAssignableTo(DubPred) etc.

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
tests/lib/mirrors/relation_assignable_test.dart:109:
Expect.isTrue(DubGen.isAssignableTo(Obj));
Again, the inverse holds as well.

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
tests/lib/mirrors/relation_assignable_test.dart:246: TypeMirror Void =
currentMirrorSystem().voidType;
Void vs. Void?

Also there are some special cases around functions that return void.

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
File tests/lib/mirrors/relation_subtype_test.dart (right):

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
tests/lib/mirrors/relation_subtype_test.dart:244:
Expect.isFalse(Dynamic.isSubtypeOf(TFromC));
All of the Dynamic.isSubtypeOf(X) cases should be true, since bottom is
substituted for dynamic.

https://codereview.chromium.org/126823004/diff/80007/tests/lib/mirrors/relati...
tests/lib/mirrors/relation_subtype_test.dart:286:
Expect.isFalse(Dynamic.isSubtypeOf(Void));
should be true

[ahe, 2014-01-13 15:00:34]

I'm not sure we should be adding more API at this time.

I think there are some big issues about existing features that needs to be
worked out before we consider adding new API.

[regis, 2014-01-13 17:48:37]

LGTM

[rmacnak, 2014-01-14 01:04:06]

Updated tests per comments, plus to silence the analyzer.

[gbracha, 2014-01-14 01:19:01]

tests lgtm.

[rmacnak, 2014-02-06 23:15:23]

+Johnni re source mirrors implementation

Noted some disagreements between the implementations to ask Gilad about when he
returns.

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
File tests/lib/mirrors/relation_assignable_test.dart (right):

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
tests/lib/mirrors/relation_assignable_test.dart:274: //
Expect.isFalse(Obj.isAssignableTo(Void)); // dart2js disagrees
Disagreement.

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
tests/lib/mirrors/relation_assignable_test.dart:293: //
Expect.isFalse(Void.isAssignableTo(Obj)); // dart2js disagrees
Disagreement.

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
File tests/lib/mirrors/relation_subclass_test.dart (right):

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
tests/lib/mirrors/relation_subclass_test.dart:91: // The source mirrors
disagree.
Disagreement.

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
File tests/lib/mirrors/relation_subtype_test.dart (right):

https://codereview.chromium.org/126823004/diff/370001/tests/lib/mirrors/relat...
tests/lib/mirrors/relation_subtype_test.dart:277: //
Expect.isFalse(Void.isSubtypeOf(Obj));  // Dart2js disagrees
Disagreement.

[Johnni Winther, 2014-02-07 11:20:20]

lgtm

[rmacnak, 2014-02-11 20:41:46]

Committed patchset #9 manually as r32577 (presubmit successful).