[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 6991518178e38298ca7d00442c65371bba1914e4..eca09fcb8dddffd0746350d6d3b6f8e780a08ca6 100644
--- a/runtime/vm/kernel_to_il.cc
+++ b/runtime/vm/kernel_to_il.cc
@@ -812,7 +812,7 @@ 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();