Remove unneeded generation of default constructors from the dart backend.

Remove unneeded generation of default constructors from the dart backend.

BUG=
R=sigurdm@google.com

Committed: https://code.google.com/p/dart/source/detail?r=39737

[Johnni Winther, 2014-09-02 08:46:56]

johnniwinther@google.com changed reviewers:
+ sigurdm@google.com

[sigurdm, 2014-09-02 09:14:07]

LGTM

https://codereview.chromium.org/526263002/diff/1/tests/compiler/dart2js/backe...
File tests/compiler/dart2js/backend_dart/dart_backend_test.dart (right):

https://codereview.chromium.org/526263002/diff/1/tests/compiler/dart2js/backe...
tests/compiler/dart2js/backend_dart/dart_backend_test.dart:881:
testUnresolvedNamedConstructor1() {
Maybe it is nicer to keep the class alive with a static:

class A {
  A() {}
  static foo() {}
}

main() {
  A.foo();
  new A.named()
}

==>

class A {
  static foo() {}
}

main() {
  A.foo();
  new unresolved();
}

https://codereview.chromium.org/526263002/diff/1/tests/compiler/dart2js/backe...
tests/compiler/dart2js/backend_dart/dart_backend_test.dart:951: }
Could also make a language-test (might already exist):

class A {
  A.named();
  static foo() {}
}

main() {
  A.foo();
  Expect.throws(() => new A());
}

[Johnni Winther, 2014-09-02 10:01:31]

Committed patchset #3 manually as 39737 (presubmit successful).