Change dart2js_foreign suite to use metadata.

Change dart2js_foreign suite to use metadata.

Committed: https://code.google.com/p/dart/source/detail?r=11026

[ahe, 2012-08-20 21:30:11]

Consider if we want to use different metadata tags for different things. Right
now, it is as overloaded as the original keyword.

[sra1, 2012-08-21 00:56:14]

I'm OK with this as is, or with some changes.
I'm not sure what naming convention we want to use for multi-word metadata
annotations.

@native_body would be a good candidate to split out - writing a body in
JavaScript is orthogonal to having a specific name in JavaScript.

https://chromiumcodereview.appspot.com/10823423/diff/1/dart/tests/compiler/da...
File dart/tests/compiler/dart2js_foreign/native_call_arity1_test.dart (right):

https://chromiumcodereview.appspot.com/10823423/diff/1/dart/tests/compiler/da...
dart/tests/compiler/dart2js_foreign/native_call_arity1_test.dart:13:
@native("*A")
@native_type_tag("*A")
@nativeTypeTag("*A")

The class is a native class identified by this type tag.

Also on classes:

@nativeException

The class might be thrown by calls to native code so you can't tree-shake it. 
In dart:html there is no way for us to tell which exceptions are thrown by which
methods.  It is declared in the IDL but there is no enforcement so I don't
believe the types.

https://chromiumcodereview.appspot.com/10823423/diff/1/dart/tests/compiler/da...
dart/tests/compiler/dart2js_foreign/native_call_arity1_test.dart:29: @native("""
@native_body

Although I would like to deprecate this, it is difficult to see how you could
conveniently write these tests.
Most remaining cases in dart:html can be rewritten to avoid this case.

[kasperl, 2012-08-21 05:53:59]

LGTM. I agree with Stephen that using annotations allow us to start having
multiple different native tags, which seems extremely useful.

[ngeoffray, 2012-08-21 06:34:18]

STV! Thanks Peter for doing this. Once that's in, we can refine the annotations
for all the different cases.

[ahe, 2012-08-21 10:14:14]

I agree, we shouldn't use @native for everything. But I'll focus on providing
making metadata available, and leave it to others to convert our native
implementation to use metadata.

One more thing: I think it would be nice to avoid "*A" on classes. I feel it
would be better if there was a separate metadata tag for each kind of symbol
that can be used in that position, so instead of:

@native("*A") you would write @nativeClass("A")

@native("@*DOMWindow") you would write
@nativeAsIfIKnowWhatThisMeans("DOMWindow").