bindings: Throw TypeError when required dictionary member is undefined

Source/bindings/scripts/idl_definitions.py

Index: Source/bindings/scripts/idl_definitions.py
diff --git a/Source/bindings/scripts/idl_definitions.py b/Source/bindings/scripts/idl_definitions.py
index 630bc8482ca3732d97f28478512536b4874ba2bc..25e4d13eebea8f4a01cb3e564609c7c61c5a47e6 100644
--- a/Source/bindings/scripts/idl_definitions.py
+++ b/Source/bindings/scripts/idl_definitions.py
@@ -222,6 +222,7 @@ class IdlDictionaryMember(TypedObject):
         self.extended_attributes = {}
         self.idl_type = None
         self.idl_name = idl_name
+        self.is_required = bool(node.GetProperty('REQUIRED'))
         self.name = node.GetName()
         for child in node.GetChildren():
             child_class = child.GetClass()