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

tests/compiler/dart2js/js_backend_cps_ir_constructor_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.
 // VMOptions=-DUSE_CPS_IR=true
 
 // Tests of interceptors.
 
 library constructor_test;
 
 import 'js_backend_cps_ir.dart';
@@ skipping 52 matching lines @@
     print(x);
   }
 }
 main() {
   print(new Sub(1, 2).x);
 }""",
 r"""
 function(x, y) {
   var v0;
   v0 = new V.Sub(y, x);
-  v0.Base0$0();
-  v0.Sub$2(x, y);
+  v0.Base0();
+  v0.Sub(x, y);
   return v0;
 }"""),
 
   const TestEntry.forMethod('generative_constructor(Sub#)', """
 class Base0 {
   Base0() {
     print('Base0');
   }
 }
 class Base extends Base0 {
@@ skipping 10 matching lines @@
 }
 main() {
   print(new Sub(1, 2).x);
 }""",
 r"""
 function(x, y) {
   var box_0, v0;
   box_0 = {};
   box_0.x1_0 = x;
   v0 = new V.Sub(y, new V.Base_closure(box_0));
-  v0.Base0$0();
-  v0.Base$1(box_0);
-  v0.Sub$2(x, y);
+  v0.Base0();
+  v0.Base(box_0);
+  v0.Sub(x, y);
   return v0;
 }"""),
 
   const TestEntry.forMethod('generative_constructor(Sub#)', """
 foo(x) {
   print(x);
 }
 class Base {
   var x1 = foo('x1');
   var x2;
@@ skipping 18 matching lines @@
   v2 = V.foo("x1");
   v3 = V.foo("x3");
   v4 = V.foo("x2");
   return new V.Sub(v0, v1, V.foo("y3"), v2, v4, v3);
 }"""),
 ];
 
 void main() {
   runTests(tests);
 }