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

runtime/vm/service.cc

Index: runtime/vm/service.cc
diff --git a/runtime/vm/service.cc b/runtime/vm/service.cc
index fe24ad50bccec872c066d1292279f343b1873a33..6dd4f5f98e75c7f04b5441ca79a3977ce787c58f 100644
--- a/runtime/vm/service.cc
+++ b/runtime/vm/service.cc
@@ -2559,6 +2559,7 @@ static const MethodParameter* reload_sources_params[] = {
 };
 
 static bool ReloadSources(Thread* thread, JSONStream* js) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
   Isolate* isolate = thread->isolate();
   if (!isolate->compilation_allowed()) {
     js->PrintError(kFeatureDisabled,
@@ -2596,6 +2597,11 @@ static bool ReloadSources(Thread* thread, JSONStream* js) {
   Service::CheckForPause(isolate, js);
 
   return true;
+#else   // !defined(DART_PRECOMPILED_RUNTIME)
+  js->PrintError(kFeatureDisabled,
+                 "This isolate cannot reload sources right now.");
+  return true;
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
 }
 
 void Service::CheckForPause(Isolate* isolate, JSONStream* stream) {