Make PropertyCell::UpdatedType return a handle.

src/stub-cache.cc

Index: src/stub-cache.cc
diff --git a/src/stub-cache.cc b/src/stub-cache.cc
index bac274c31a6797465207eaf2141fa65c1fd4a988..67002a36b17abdba2a2a136ff226f00ed2237d5f 100644
--- a/src/stub-cache.cc
+++ b/src/stub-cache.cc
@@ -267,8 +267,7 @@ Handle<Code> StubCache::ComputeStoreGlobal(Handle<Name> name,
                                            Handle<PropertyCell> cell,
                                            Handle<Object> value,
                                            StrictModeFlag strict_mode) {
-  Isolate* isolate = cell->GetIsolate();
-  Handle<Type> union_type(PropertyCell::UpdatedType(cell, value), isolate);
+  Handle<Type> union_type = PropertyCell::UpdatedType(cell, value);
   bool is_constant = union_type->IsConstant();
   StoreGlobalStub stub(strict_mode, is_constant);