Fix method inference crasher

Fix method inference crasher.

During class member inference, only instantiate the type formals of
an overridden method when there are type formals to instantiate.

BUG=
R=jmesserly@google.com

Committed: https://github.com/dart-lang/sdk/commit/6a9af860d04cd2258f5cae74993677272c704832

[Leaf, 2016-03-04 22:54:25]

Description was changed from

==========
Fix method inference crasher

BUG=
==========

to

==========
Fix method inference crasher.

During class member inference, only instantiate the type formals of
an overridden method when there are type formals to instantiate.

BUG=
==========

[Leaf, 2016-03-04 22:54:25]

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

[Jennifer Messerly, 2016-03-06 20:20:19]

lgtm

https://codereview.chromium.org/1763013003/diff/1/pkg/analyzer/test/src/task/...
File pkg/analyzer/test/src/task/strong/inferred_type_test.dart (right):

https://codereview.chromium.org/1763013003/diff/1/pkg/analyzer/test/src/task/...
pkg/analyzer/test/src/task/strong/inferred_type_test.dart:1845: /*=T*/
m/*<T>*/(/*=T*/ x) => x;
do/should we also have test cases for when the parameter/return type from C is
actually pushed down to D?

[Leaf, 2016-03-07 18:40:28]

https://codereview.chromium.org/1763013003/diff/1/pkg/analyzer/test/src/task/...
File pkg/analyzer/test/src/task/strong/inferred_type_test.dart (right):

https://codereview.chromium.org/1763013003/diff/1/pkg/analyzer/test/src/task/...
pkg/analyzer/test/src/task/strong/inferred_type_test.dart:1845: /*=T*/
m/*<T>*/(/*=T*/ x) => x;
On 2016/03/06 20:20:19, John Messerly wrote:
> do/should we also have test cases for when the parameter/return type from C is
> actually pushed down to D?

Yes, there's one above ("infer generic method type").

[Leaf, 2016-03-07 18:50:01]

Description was changed from

==========
Fix method inference crasher.

During class member inference, only instantiate the type formals of
an overridden method when there are type formals to instantiate.

BUG=
==========

to

==========
Fix method inference crasher.

During class member inference, only instantiate the type formals of
an overridden method when there are type formals to instantiate.

BUG=
R=jmesserly@google.com

Committed:
https://github.com/dart-lang/sdk/commit/6a9af860d04cd2258f5cae74993677272c704832
==========

[Leaf, 2016-03-07 18:50:02]

Committed patchset #1 (id:1) manually as
6a9af860d04cd2258f5cae74993677272c704832 (presubmit successful).