dart2js: Ensure each use site of a name uses a new ast node.

pkg/compiler/lib/src/js_backend/namer_names.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.
 
 part of js_backend;
 
 abstract class _NamerName extends jsAst.Name {
   int get _kind;
+  _NamerName get _target => this;
 
   toString() => throw new UnsupportedError("Cannot convert a name to a string");
 }
 
 enum _NamerNameKinds {
   StringBacked,
   Getter,
   Setter,
   Async,
   Compound,
   Token
 }
 
 class StringBackedName extends _NamerName {
   final String name;
   int get _kind => _NamerNameKinds.StringBacked.index;
 
   StringBackedName(this.name);
 
   String get key => name;
 
   operator==(other) {
+    if (other is _NameReference) other = other._target;
     if (identical(this, other)) return true;
     return (other is StringBackedName) && other.name == name;
   }
 
   int get hashCode => name.hashCode;
 
   int compareTo(_NamerName other) {
+    other = other._target;
     if (other._kind != _kind) return other._kind - _kind;
     return name.compareTo(other.name);
   }
 }
 
 abstract class _PrefixedName extends _NamerName implements jsAst.AstContainer {
   final jsAst.Name prefix;
   final jsAst.Name base;
   int get _kind;
 
   Iterable<jsAst.Node> get containedNodes => [prefix, base];
 
   _PrefixedName(this.prefix, this.base);
 
   String get name => prefix.name + base.name;
 
   String get key => prefix.key + base.key;
 
   bool operator==(other) {
+    if (other is _NameReference) other = other._target;
     if (identical(this, other)) return true;
     if (other is! _PrefixedName) return false;
     return other.base == base && other.prefix == prefix;
   }
 
   int get hashCode => base.hashCode * 13 + prefix.hashCode;
 
   int compareTo(_NamerName other) {
+    other = other._target;
     if (other._kind != _kind) return other._kind - _kind;
     _PrefixedName otherSameKind = other;
     int result = prefix.compareTo(otherSameKind.prefix);
     if (result == 0) {
       result = prefix.compareTo(otherSameKind.prefix);
       if (result == 0) {
         result = base.compareTo(otherSameKind.base);
       }
     }
     return result;
@@ skipping 34 matching lines @@
   String get name {
     if (_cachedName == null) {
       _cachedName = _parts.map((jsAst.Name name) => name.name).join();
     }
     return _cachedName;
   }
 
   String get key => _parts.map((_NamerName name) => name.key).join();
 
   bool operator==(other) {
+    if (other is _NameReference) other = other._target;
     if (identical(this, other)) return true;
     if (other is! CompoundName) return false;
     if (other._parts.length != _parts.length) return false;
     for (int i = 0; i < _parts.length; ++i) {
       if (other._parts[i] != _parts[i]) return false;
     }
     return true;
   }
 
   int get hashCode {
     if (_cachedHashCode < 0) {
       _cachedHashCode = 0;
       for (jsAst.Name name in _parts) {
         _cachedHashCode = (_cachedHashCode * 17 + name.hashCode) & 0x7fffffff;
       }
     }
     return _cachedHashCode;
   }
 
   int compareTo(_NamerName other) {
+    other = other._target;
     if (other._kind != _kind) return other._kind - _kind;
     CompoundName otherSameKind = other;
     if (otherSameKind._parts.length != _parts.length) {
       return otherSameKind._parts.length - _parts.length;
     }
     int result = 0;
     for (int pos = 0; result == 0 && pos < _parts.length; pos++) {
       result = _parts[pos].compareTo(otherSameKind._parts[pos]);
     }
     return result;
@@ skipping 11 matching lines @@
 
   bool get isFinalized => _name != null;
 
   String get name {
     assert(isFinalized);
     return _name;
   }
 
   @override
   int compareTo(_NamerName other) {
+    other = other._target;
     if (other._kind != _kind) return other._kind - _kind;
     TokenName otherToken = other;
     return key.compareTo(otherToken.key);
   }
 
   markSeen(jsAst.TokenCounter counter) => _rc++;
 
+  @override
+  bool operator==(other) {
+    if (other is _NameReference) other = other._target;
+    if (identical(this, other)) return true;
+    return false;
+  }
+
+  @override
+  int get hashCode => super.hashCode;
+
   finalize() {
     assert(!isFinalized);
     _name = _scope.getNextName();
   }
+}
+
+class _NameReference extends _NamerName implements jsAst.AstContainer {
+  _NamerName _target;
+
+  int get _kind => _target._kind;
+  String get key => _target.key;
+
+  Iterable<jsAst.Node> get containedNodes => [_target];
+
+  _NameReference(this._target);
+
+  String get name => _target.name;
+
+  @override
+  int compareTo(_NamerName other) => _target.compareTo(other);
+
+  @override
+  bool operator==(other) => _target == other;
+
+  @override
+  int get hashCode => _target.hashCode;
 }