[kernel] Change how TypeParameterType is calculated.

runtime/vm/kernel_to_il.cc

Index: runtime/vm/kernel_to_il.cc
diff --git a/runtime/vm/kernel_to_il.cc b/runtime/vm/kernel_to_il.cc
index bfa7743885e4a8fa5e6f9b3da7147297418bd1db..17d04342d0e91382c49f79b9ec116edcc74742d0 100644
--- a/runtime/vm/kernel_to_il.cc
+++ b/runtime/vm/kernel_to_il.cc
@@ -761,7 +761,7 @@ Fragment FlowGraphBuilder::LoadInstantiatorTypeArguments() {
 #endif
     instructions += LoadLocal(scopes_->type_arguments_variable);
   } else if (scopes_->this_variable != NULL &&
-             active_class_.class_type_parameters > 0) {
+             active_class_.ClassTypeParameterCount(Z) > 0) {
     ASSERT(!parsed_function_->function().IsFactory());
     intptr_t type_arguments_field_offset =
         active_class_.klass->type_arguments_field_offset();