dart2js: Refactoring, documentation, and a few bugfixes in Namer class.

tests/language/constructor_name_clash_test.dart

 // Copyright (c) 2015, 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.
 
-import 'dart:math' as Math;
 import 'package:expect/expect.dart';
+import 'constructor_name_clash_lib.dart' as lib;
+
+class A extends lib.A {
+  A() {
+    lib.global += 100;
+    try {} catch(e) {} // no inline
+  }
+}
 
 main() {
-  Expect.equals(4, new C().m());
+  new A();
+  Expect.equals(110, lib.global);
 }
-
-class C {
-  max(a) => a;
-
-  m() {
-    return max(Math.max(2, 4));
-  }
-}