Support nullable attributes and return types in Dartium.

tools/dom/scripts/idlnode.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.
 
 import os
 import sys
 
 
 class IDLNode(object):
@@ skipping 315 matching lines @@
     self.arguments = self._convert_all(arg_list_ast, 'Argument', IDLArgument)
 
 
 class IDLType(IDLNode):
   """IDLType is used to describe constants, attributes and operations'
   return and input types. IDLType matches AST labels such as ScopedName,
   StringType, VoidType, IntegerType, etc."""
 
   def __init__(self, ast):
     IDLNode.__init__(self, ast)
+    self.nullable = self._has(ast, 'Nullable')
     # Search for a 'ScopedName' or any label ending with 'Type'.
     if isinstance(ast, list):
       self.id = self._find_first(ast, 'ScopedName')
       if not self.id:
         # FIXME: use regexp search instead
         def findType(ast):
           for label, childAst in ast:
             if label.endswith('Type'):
               type = self._label_to_type(label, ast)
               if type != 'sequence':
@@ skipping 180 matching lines @@
   """IDLDictNode specialization for one annotation."""
   def __init__(self, ast=None):
     IDLDictNode.__init__(self, ast)
     self.id = None
     if not ast:
       return
     for arg in self._find_all(ast, 'AnnotationArg'):
       name = self._find_first(arg, 'Id')
       value = self._find_first(arg, 'AnnotationArgValue')
       self[name] = value