IDL: Use IdlNullableType wrapper to represent nullable types

Source/bindings/scripts/v8_types.py

Index: Source/bindings/scripts/v8_types.py
diff --git a/Source/bindings/scripts/v8_types.py b/Source/bindings/scripts/v8_types.py
index 5f930d324866e2c464a5fc00dbfe2af65cc1d62c..569cac22c7306aa96dba3791a0057bcfa5320845 100644
--- a/Source/bindings/scripts/v8_types.py
+++ b/Source/bindings/scripts/v8_types.py
@@ -39,7 +39,7 @@ Design doc: http://www.chromium.org/developers/design-documents/idl-compiler
 
 import posixpath
 
-from idl_types import IdlTypeBase, IdlType, IdlUnionType, IdlArrayOrSequenceType
+from idl_types import IdlTypeBase, IdlType, IdlUnionType, IdlArrayOrSequenceType, IdlNullableType
 import v8_attributes  # for IdlType.constructor_type_name
 from v8_globals import includes
 
@@ -72,12 +72,9 @@ TYPED_ARRAYS = {
     'Uint32Array': ('unsigned int', 'v8::kExternalUnsignedIntArray'),
 }
 
-IdlTypeBase.is_typed_array_element_type = False
 IdlType.is_typed_array_element_type = property(
     lambda self: self.base_type in TYPED_ARRAYS)
 
-
-IdlTypeBase.is_wrapper_type = False
 IdlType.is_wrapper_type = property(
     lambda self: (self.is_interface_type and
                   self.base_type not in NON_WRAPPER_TYPES))
@@ -239,7 +236,6 @@ IdlUnionType.cpp_type_initializer = property(cpp_type_initializer_union)
 IdlUnionType.cpp_type_args = cpp_type_union
 
 
-IdlTypeBase.native_array_element_type = None
 IdlArrayOrSequenceType.native_array_element_type = property(
     lambda self: self.element_type)
 
@@ -295,7 +291,6 @@ IdlType.set_implemented_as_interfaces = classmethod(
 # [GarbageCollected]
 IdlType.garbage_collected_types = set()
 
-IdlTypeBase.is_garbage_collected = False
 IdlType.is_garbage_collected = property(
     lambda self: self.base_type in IdlType.garbage_collected_types)
 
@@ -307,7 +302,6 @@ IdlType.set_garbage_collected_types = classmethod(
 # [WillBeGarbageCollected]
 IdlType.will_be_garbage_collected_types = set()
 
-IdlTypeBase.is_will_be_garbage_collected = False
 IdlType.is_will_be_garbage_collected = property(
     lambda self: self.base_type in IdlType.will_be_garbage_collected_types)
 
@@ -605,7 +599,10 @@ def preprocess_idl_type_and_value(idl_type, cpp_value, extended_attributes):
     if idl_type.base_type in ['long long', 'unsigned long long']:
         # long long and unsigned long long are not representable in ECMAScript;
         # we represent them as doubles.
-        idl_type = IdlType('double', is_nullable=idl_type.is_nullable)
+        is_nullable = idl_type.is_nullable
+        idl_type = IdlType('double')
+        if is_nullable:
+            idl_type = IdlNullableType(idl_type)
         cpp_value = 'static_cast<double>(%s)' % cpp_value
     # HTML5 says that unsigned reflected attributes should be in the range
     # [0, 2^31). When a value isn't in this range, a default value (or 0)
@@ -742,7 +739,6 @@ IdlType.release = property(lambda self: self.is_interface_type)
 IdlUnionType.release = property(
     lambda self: [member_type.is_interface_type
                   for member_type in self.member_types])
-IdlArrayOrSequenceType.release = False
 
 
 CPP_VALUE_TO_V8_VALUE = {