Implement new equality spec.

Implement new equality spec. 

"If either o1 or o2 is null, then ee evaluates to identical(o1,o2), where identical() is the predefined dart function that returns true iff its two arguments are the same object. "
Committed: https://code.google.com/p/dart/source/detail?r=10907

[sra1, 2012-08-17 01:34:08]

https://chromiumcodereview.appspot.com/10855208/diff/6001/tests/language/equa...
File tests/language/equality_test.dart (right):

https://chromiumcodereview.appspot.com/10855208/diff/6001/tests/language/equa...
tests/language/equality_test.dart:24: Expect.isFalse(null != null);
Should also compare cases where both sides are expressions that are opaque to
the optimizer but one evaluates to 'null' (to avoid testing only code-gen for
comparison to constants).

E.g.


opaque(x) => [x,1,'y'][0];  // Whatever it takes to confuse the compiler, now
and in the foreseeable future.

class Death {
  operator ==(x) { throw 'Dead!'; }
}

death() => opaque(new Death());
nullFn() => opaque(null);

Expect.isFalse(death() == nullFn());
Expect.isFalse(nullFn() == death());
Expect.isTrue(nullFn() == nullFn());
Expect.throws(death() == 5);

[regis, 2012-08-17 01:53:44]

LGTM

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
File runtime/vm/intermediate_language_ia32.cc (right):

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
runtime/vm/intermediate_language_ia32.cc:315: } else {
Code is easier to read if you document this branch with
ASSERT(comp->kind() == Token::kNE);

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
File runtime/vm/intermediate_language_x64.cc (right):

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
runtime/vm/intermediate_language_x64.cc:324: } else {
ditto

[srdjan, 2012-08-17 17:26:41]

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
File runtime/vm/intermediate_language_ia32.cc (right):

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
runtime/vm/intermediate_language_ia32.cc:315: } else {
On 2012/08/17 01:53:45, regis wrote:
> Code is easier to read if you document this branch with
> ASSERT(comp->kind() == Token::kNE);

Done.

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
File runtime/vm/intermediate_language_x64.cc (right):

https://chromiumcodereview.appspot.com/10855208/diff/6001/runtime/vm/intermed...
runtime/vm/intermediate_language_x64.cc:324: } else {
On 2012/08/17 01:53:45, regis wrote:
> ditto

Done.