Migrate error messages, part 12.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 8269f27ed93c331f2e314e9abeb6c5ee8e2e03a0..4ad40423b13ccb21ecfb03540682c6c5cd94d838 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1560,7 +1560,8 @@ Local<Script> UnboundScript::BindToCurrentContext() {
         pending_error_handler_.ReportMessageAt(
             scope_info->StrongModeFreeVariableStartPosition(i),
             scope_info->StrongModeFreeVariableEndPosition(i),
-            "strong_unbound_global", name_string, i::kReferenceError);
+            i::MessageTemplate::kStrongUnboundGlobal, name_string,
+            i::kReferenceError);
         i::Handle<i::Script> script(i::Script::cast(function_info->script()));
         pending_error_handler_.ThrowPendingError(isolate, script);
         isolate->ReportPendingMessages();