WebKit IDL roll.

tools/dom/scripts/generator.py

Index: tools/dom/scripts/generator.py
diff --git a/tools/dom/scripts/generator.py b/tools/dom/scripts/generator.py
index d8c213b19cc6c663d0e18064bc07490fa98cf5e0..517c66ac3c7e027739d31dc57591082918d084d1 100644
--- a/tools/dom/scripts/generator.py
+++ b/tools/dom/scripts/generator.py
@@ -149,6 +149,8 @@ def _BuildArguments(args, interface, constructor=False):
       # FIXME: Optional constructors arguments should not be treated as
       # optional arguments.
       return argument.optional
+    if 'ForceOptional' in argument.ext_attrs:
+      return True
     return False
 
   # Given a list of overloaded arguments, choose a suitable name.
@@ -182,7 +184,8 @@ def _BuildArguments(args, interface, constructor=False):
   return result
 
 def IsOptional(argument):
-  return argument.optional and ('Default' not in argument.ext_attrs)
+  return argument.optional and ('Default' not in argument.ext_attrs)\
+      or 'ForceOptional' in argument.ext_attrs
 
 def AnalyzeOperation(interface, operations):
   """Makes operation calling convention decision for a set of overloads.