Add optional arguments to our indexOf/lastIndexOf methods.

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 1262 matching lines @@
         '\n'
         '  void sort(int compare($TYPE a, $TYPE b)) {\n'
         '    throw new UnsupportedOperationException("Cannot sort immutable List.");\n'
         '  }\n'
         '\n'
         '  void copyFrom(List<Object> src, int srcStart, '
         'int dstStart, int count) {\n'
         '    throw new UnsupportedOperationException("This object is immutable.");\n'
         '  }\n'
         '\n'
-        '  int indexOf($TYPE element, int startIndex) {\n'
-        '    return _Lists.indexOf(this, element, startIndex, this.length);\n'
+        '  int indexOf($TYPE element, [int start = 0]) {\n'
+        '    return _Lists.indexOf(this, element, start, this.length);\n'
         '  }\n'
         '\n'
-        '  int lastIndexOf($TYPE element, int startIndex) {\n'
-        '    return _Lists.lastIndexOf(this, element, startIndex);\n'
+        '  int lastIndexOf($TYPE element, [int start = null]) {\n'
+        '    if (start === null) start = length - 1;\n'
+        '    return _Lists.lastIndexOf(this, element, start);\n'
         '  }\n'
         '\n'
         '  int clear() {\n'
         '    throw new UnsupportedOperationException("Cannot clear immutable List.");\n'
         '  }\n'
         '\n'
         '  $TYPE removeLast() {\n'
         '    throw new UnsupportedOperationException("Cannot removeLast on immutable List.");\n'
         '  }\n'
         '\n'
@@ skipping 439 matching lines @@
       self._batched_operation_names.append(info.name)
 
   def AddSecondaryGetter(self, interface, attr):
     self.AddGetter(attr)
 
   def AddSecondarySetter(self, interface, attr):
     self.AddSetter(attr)
 
   def AddSecondaryOperation(self, interface, info):
     self.AddOperation(info)