Cleanup the namer, and add a test with fields that used to clash with internal names used by the co…

tests/language/namer2_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Test that user field names cannot clash with internal names of the
+// dart2js compiler.
+
+class A<T> {
+  var $isA;
+  var $eq;
+  var $builtinTypeInfo;
+}
+
+main() {
+  var c = [new A()];
+  Expect.isTrue(c[0] is A);
+  Expect.isTrue(c[0] == c[0]);
+  
+  c = [new A<int>()];
+  c[0].$builtinTypeInfo = 42;
+  Expect.isTrue(c[0] is! A<String>);
+}