Use isolate parameter while creating handles during class finalizers.

runtime/vm/object.cc

Index: runtime/vm/object.cc
===================================================================
--- runtime/vm/object.cc	(revision 39535)
+++ runtime/vm/object.cc	(working copy)
@@ -7747,11 +7747,13 @@
   }
   uint8_t* data = reinterpret_cast<uint8_t*>(::malloc(len));
   ASSERT(data != NULL);
+  Isolate* isolate = Isolate::Current();
   const ExternalTypedData& stream = ExternalTypedData::Handle(
+      isolate,
       ExternalTypedData::New(kExternalTypedDataUint8ArrayCid,
                              data, len, Heap::kOld));
   stream.AddFinalizer(data, DataFinalizer);
-  const TokenStream& result = TokenStream::Handle(TokenStream::New());
+  const TokenStream& result = TokenStream::Handle(isolate, TokenStream::New());
   result.SetStream(stream);
   return result.raw();
 }