Add map to dart:dom collections.

client/dom/scripts/dartgenerator.py

 #!/usr/bin/python
 # Copyright (c) 2011, 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.
 
 """This module generates Dart APIs from the IDL database."""
 
 import emitter
 import idlnode
 import logging
@@ skipping 1489 matching lines @@
         '  }\n'
         '\n'
         '  $TYPE last() {\n'
         '    return this[length - 1];\n'
         '  }\n'
         '\n'
         '  void forEach(void f($TYPE element)) {\n'
         '    _Collections.forEach(this, f);\n'
         '  }\n'
         '\n'
+        '  Collection map(f($TYPE element)) {\n'
+        '    return _Collections.map(this, [], f);\n'
+        '  }\n'
+        '\n'
         '  Collection<$TYPE> filter(bool f($TYPE element)) {\n'
         '    return _Collections.filter(this, new List<$TYPE>(), f);\n'
         '  }\n'
         '\n'
         '  bool every(bool f($TYPE element)) {\n'
         '    return _Collections.every(this, f);\n'
         '  }\n'
         '\n'
         '  bool some(bool f($TYPE element)) {\n'
         '    return _Collections.some(this, f);\n'
@@ skipping 441 matching lines @@
     Arguments:
       info: An OperationInfo object.
     """
     # TODO(vsm): Handle overloads.
     self._members_emitter.Emit(
         '\n'
         '  $TYPE $NAME($ARGS) native;\n',
         TYPE=info.type_name,
         NAME=info.name,
         ARGS=info.arg_implementation_declaration)