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

After [0] landed our debug builders managed to still compile, because
the default debug-optimization-level allows the compiler to inline. This
caused a "CanReload() const { return false; }" to be inlined and
constant folded, so the call to ReloadSources() was eliminated.

Compiling with debug-optimization-level=0 disables inlining and keeps
the call, which gives us a linker error when building the
dart_precompiled_runtime target.

[0] https://codereview.chromium.org/2997243002

[email protected]

Review-Url: https://codereview.chromium.org/3003383002 .

Author: mkustermann

runtime/vm/isolate.h

@@ -283,13 +283,15 @@ 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,
                      bool force_reload,
                      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();

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) {