Reapply 'Add runtimeType() to Object which returns canonicalized instances of Type'.

Reapply 'Add runtimeType() to Object which returns canonicalized instances of Type'.

This CL fixes a bug in https://chromiumcodereview.appspot.com/10908142/ which generated unneeded type information leading to runtime regression.

Original committed in 12491 and reverted in 

R=ngeoffray@google.com

Committed: https://code.google.com/p/dart/source/detail?r=12540

[ngeoffray, 2012-09-19 08:43:09]

LGTM!

https://chromiumcodereview.appspot.com/10941031/diff/1/lib/compiler/implement...
File lib/compiler/implementation/ssa/builder.dart (right):

https://chromiumcodereview.appspot.com/10941031/diff/1/lib/compiler/implement...
lib/compiler/implementation/ssa/builder.dart:2664: bool needsRti =
compiler.world.needsRti(element) && rtiInputs.length > 0;
isEmpty?

[karlklose, 2012-09-19 08:44:27]

https://chromiumcodereview.appspot.com/10941031/diff/1/lib/compiler/implement...
File lib/compiler/implementation/ssa/builder.dart (right):

https://chromiumcodereview.appspot.com/10941031/diff/1/lib/compiler/implement...
lib/compiler/implementation/ssa/builder.dart:2664: bool needsRti =
compiler.world.needsRti(element) && rtiInputs.length > 0;
On 2012/09/19 08:43:09, ngeoffray wrote:
> isEmpty?

Done.

[Ivan Posva, 2012-09-19 15:21:36]

The class Type was hard to find for me as it does not follow the usual pattern
and other drive by comments.

-Ivan

https://codereview.chromium.org/10941031/diff/15/lib/core/object.dart
File lib/core/object.dart (right):

https://codereview.chromium.org/10941031/diff/15/lib/core/object.dart#newcode20
lib/core/object.dart:20: abstract class Type {}
This is lacking documentation.

Also, we tend to split classes into separate files. This would not be the first
tiny class in its own file.

https://codereview.chromium.org/10941031/diff/15/tests/language/first_class_t...
File tests/language/first_class_types.dart (right):

https://codereview.chromium.org/10941031/diff/15/tests/language/first_class_t...
tests/language/first_class_types.dart:8: Expect.isTrue(a.runtimeType() ===
b.runtimeType());
Expect.identical(a.runtimeType(), b.runtimeType());

You will get much better error messages this way.