fixes #232, handling of arguments

lib/src/codegen/js_codegen.dart

Index: lib/src/codegen/js_codegen.dart
diff --git a/lib/src/codegen/js_codegen.dart b/lib/src/codegen/js_codegen.dart
index b3421f5e96af27cb25572df60a51cdd3a7c9a255..34f9534b4839ceab94b0dd3e63ae7defa0d634a6 100644
--- a/lib/src/codegen/js_codegen.dart
+++ b/lib/src/codegen/js_codegen.dart
@@ -337,10 +337,8 @@ class JSCodegenVisitor extends GeneralizingAstVisitor {
     if (!supertype.isObject) {
       for (var ctor in element.constructors) {
         var parentCtor = supertype.lookUpConstructor(ctor.name, ctor.library);
-        var fun = js.call('function() { super.#(...#); }', [
-          _constructorName(parentCtor),
-          new JS.Identifier('arguments', allowRename: false)
-        ]);
+        var fun = js.call('function() { super.#(...arguments); }',
+            [_constructorName(parentCtor)]);
         body.add(new JS.Method(_constructorName(ctor), fun));
       }
     }
@@ -845,16 +843,14 @@ class JSCodegenVisitor extends GeneralizingAstVisitor {
       // Performance of this pattern is likely to be bad.
       name = _propertyName('constructor');
       // Mark the parameter as no-rename.
-      var args = new JS.Identifier('arguments', allowRename: false);
       body = js.statement('''{
         // Get the class name for this instance.
         let name = this.constructor.name;
         // Call the default constructor.
-        let init = this[name];
         let result = void 0;
-        if (init) result = init.apply(this, #);
+        if (name in this) result = this[name](...arguments);

[vsm, 2015/06/23 19:58:27]

Shouldn't this be something like:

if (this.__proto__.hasOwnProperty(name)) ....

?

I think we'd handle the following wrong otherwise:

class Base {
  Derived() => print("This shouldn't be called");
}

class Derived extends Base {}

main() => print(new Derived());

[Jennifer Messerly, 2015/06/23 20:08:35]

the problem, if it repros, already exists in old code. The solution would be to
make sure initialize method is generated in that case (it might already be. not
sure), and/or rename it (e.g. a dart.initialize symbol). I'd hate to need a
hasOwnProperty check here... that would probably add more overhead to this
already-crazy code path. Fortunately we have a few issues tracking cleanup here.

anyway, I can revert this if you want, just figured it would be nice to use
spread instead of .apply. I definitely don't want to get into the business of
fixing constructors in this CL, though :)

         return result === void 0 ? this : result;
-      }''', args);
+      }''');
     } else {
       body = _emitConstructorBody(node, fields);
     }