[VM] Make us compile with debug-optimization-level=0 again

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 3347f17b478cd6177c96f520534673f92677fcf5..b70c7b2e5a850b37ae0edd89c18316d505b1483c 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -283,6 +283,7 @@ class Isolate : public BaseIsolate {
   void DoneLoading();
   void DoneFinalizing();
 
+#if !defined(PRODUCT) && !defined(DART_PRECOMPILED_RUNTIME)
   // By default the reload context is deleted. This parameter allows
   // the caller to delete is separately if it is still needed.
   bool ReloadSources(JSONStream* js,
@@ -290,6 +291,7 @@ class Isolate : public BaseIsolate {
                      const char* root_script_url = NULL,
                      const char* packages_url = NULL,
                      bool dont_delete_reload_context = false);
+#endif  // !defined(PRODUCT) && !defined(DART_PRECOMPILED_RUNTIME)
 
   bool MakeRunnable();
   void Run();