Ensure 'raises' clauses on operations are saved in IDL database.

client/dom/scripts/idlrenderer.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.
 
 from idlnode import *
 
 
 def render(idl_node, indent_str='  '):
   output = []
@@ skipping 121 matching lines @@
       w(node.ext_attrs)
       if node.is_static:
         w('static ')
       if node.specials:
         w(node.specials, ' ')
         w(' ')
       w('%s ' % node.type.id)
       w(node.id)
       w('(')
       w(node.arguments, ', ')
-      wln(');')
+      w(')')
+      if node.raises:
+        w(' raises (%s)' % node.raises.id)
+      wln(';')
+
     elif isinstance(node, IDLArgument):
       w(node.ext_attrs)
       w('in ')
       if node.is_optional:
         w('optional ')
       w('%s %s' % (node.type.id, node.id))
     else:
       raise TypeError("Expected str or IDLNode but %s found" %
         type(node))
 
   w(idl_node)
   return ''.join(output)