Extend ScalarValueString handling to include constructors.

Source/bindings/scripts/idl_types.py

Index: Source/bindings/scripts/idl_types.py
diff --git a/Source/bindings/scripts/idl_types.py b/Source/bindings/scripts/idl_types.py
index e488e33264830157b37294bf42dd24c86ce5ac9d..9de8efc16d3feaba5c400b431b04c6217290b98a 100644
--- a/Source/bindings/scripts/idl_types.py
+++ b/Source/bindings/scripts/idl_types.py
@@ -70,6 +70,14 @@ TYPE_NAMES = {
     'Date': 'Date',
 }
 
+STRING_TYPES = frozenset([
+    # http://heycam.github.io/webidl/#es-interface-call (step 10.11)
+    # (Interface object [[Call]] method's string types.)
+    'String',
+    'ByteString',
+    'ScalarValueString',
+])
+
 
 ################################################################################
 # Inheritance
@@ -195,17 +203,30 @@ class IdlType(object):
                    self.name == 'Promise')  # Promise will be basic in future
 
     @property
+    def is_string_type(self):
+        return self.base_type_name in STRING_TYPES
+
+    @property
+    def may_raise_exception_on_conversion(self):
+        return (self.is_integer_type or
+                self.name in ('ByteString', 'ScalarValueString'))
+
+    @property
     def is_union_type(self):
         return isinstance(self, IdlUnionType)
 
     @property
+    def base_type_name(self):
+        base_type = self.base_type
+        return TYPE_NAMES.get(base_type, base_type)
+
+    @property
     def name(self):
         """Return type name.
 
         http://heycam.github.io/webidl/#dfn-type-name
         """
-        base_type = self.base_type
-        base_type_name = TYPE_NAMES.get(base_type, base_type)
+        base_type_name = self.base_type_name
         if self.is_array:
             return base_type_name + 'Array'
         if self.is_sequence: