IDL: Null values should be converted for non-nullable dictionary members (re-land)

Source/bindings/scripts/v8_dictionary.py

Index: Source/bindings/scripts/v8_dictionary.py
diff --git a/Source/bindings/scripts/v8_dictionary.py b/Source/bindings/scripts/v8_dictionary.py
index 0cddb519b368e1d0248fea8db776634aafc7b52b..e45bd5d618453f8a6e52e7b801d6c168bf44feb8 100644
--- a/Source/bindings/scripts/v8_dictionary.py
+++ b/Source/bindings/scripts/v8_dictionary.py
@@ -28,6 +28,13 @@ def setter_name_for_dictionary_member(member):
     return 'set%s' % v8_utilities.capitalize(name)
 
 
+def null_setter_name_for_dictionary_member(member):
+    if member.idl_type.is_nullable:
+        name = v8_utilities.cpp_name(member)
+        return 'set%sToNull' % v8_utilities.capitalize(name)
+    return None
+
+
 def has_method_name_for_dictionary_member(member):
     name = v8_utilities.cpp_name(member)
     return 'has%s' % v8_utilities.capitalize(name)
@@ -68,7 +75,7 @@ def dictionary_context(dictionary, interfaces_info):
 def member_context(member):
     idl_type = member.idl_type
     idl_type.add_includes_for_type()
-    idl_type = unwrap_nullable_if_needed(idl_type)
+    unwrapped_idl_type = unwrap_nullable_if_needed(idl_type)
 
     def default_values():
         if not member.default_value:
@@ -76,7 +83,7 @@ def member_context(member):
         if member.default_value.is_null:
             return None, 'v8::Null(isolate)'
         cpp_default_value = str(member.default_value)
-        v8_default_value = idl_type.cpp_value_to_v8_value(
+        v8_default_value = unwrapped_idl_type.cpp_value_to_v8_value(
             cpp_value=cpp_default_value, isolate='isolate',
             creation_context='creationContext')
         return cpp_default_value, v8_default_value
@@ -87,19 +94,21 @@ def member_context(member):
     return {
         'cpp_default_value': cpp_default_value,
         'cpp_name': cpp_name,
-        'cpp_type': idl_type.cpp_type,
-        'cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
+        'cpp_type': unwrapped_idl_type.cpp_type,
+        'cpp_value_to_v8_value': unwrapped_idl_type.cpp_value_to_v8_value(
             cpp_value='impl.%s()' % cpp_name, isolate='isolate',
             creation_context='creationContext',
             extended_attributes=member.extended_attributes),
-        'enum_validation_expression': idl_type.enum_validation_expression,
+        'enum_validation_expression': unwrapped_idl_type.enum_validation_expression,
         'has_method_name': has_method_name_for_dictionary_member(member),
-        'is_object': idl_type.name == 'Object',
+        'is_nullable': idl_type.is_nullable,
+        'is_object': unwrapped_idl_type.name == 'Object',
         'name': member.name,
         'setter_name': setter_name_for_dictionary_member(member),
-        'use_output_parameter_for_result': idl_type.use_output_parameter_for_result,
+        'null_setter_name': null_setter_name_for_dictionary_member(member),
+        'use_output_parameter_for_result': unwrapped_idl_type.use_output_parameter_for_result,
         'v8_default_value': v8_default_value,
-        'v8_value_to_local_cpp_value': idl_type.v8_value_to_local_cpp_value(
+        'v8_value_to_local_cpp_value': unwrapped_idl_type.v8_value_to_local_cpp_value(
             member.extended_attributes, member.name + 'Value',
             member.name, isolate='isolate'),
     }
@@ -165,6 +174,7 @@ def member_impl_context(member, interfaces_info, header_includes):
         'is_object': is_object,
         'is_traceable': idl_type.is_traceable,
         'member_cpp_type': member_cpp_type(),
+        'null_setter_name': null_setter_name_for_dictionary_member(member),
         'rvalue_cpp_type': idl_type.cpp_type_args(used_as_rvalue_type=True),
         'setter_name': setter_name_for_dictionary_member(member),
     }