Add a runtime flag to control availability of dart:mirrors.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 5448 matching lines @@
   // Now that the newly loaded classes are finalized, notify the debugger
   // that new code has been loaded. If there are latent breakpoints in
   // the new code, the debugger convert them to unresolved source breakpoints.
   // The code that completes the futures (invoked below) may call into the
   // newly loaded code and trigger one of these breakpoints.
   isolate->debugger()->NotifyDoneLoading();
 
   // Notify mirrors that MirrorSystem.libraries needs to be recomputed.
   const Library& libmirrors =
       Library::Handle(isolate, Library::MirrorsLibrary());
-  const Field& dirty_bit = Field::Handle(isolate,
-      libmirrors.LookupLocalField(String::Handle(String::New("dirty"))));
-  ASSERT(!dirty_bit.IsNull() && dirty_bit.is_static());
-  dirty_bit.set_value(Bool::True());
+  if (!libmirrors.IsNull()) {

[Ivan Posva, 2015/05/29 06:02:25]

Here we are not relying on the flag being set, but on the fact that the mirrors
library is null instead of the flag value, which makes me think that we should
reset it as necessary.

+    const Field& dirty_bit = Field::Handle(isolate,
+        libmirrors.LookupLocalField(String::Handle(String::New("dirty"))));
+    ASSERT(!dirty_bit.IsNull() && dirty_bit.is_static());
+    dirty_bit.set_value(Bool::True());
+  }
 
   if (complete_futures) {
     const Library& corelib = Library::Handle(isolate, Library::CoreLibrary());
     const String& function_name =
         String::Handle(isolate, String::New("_completeDeferredLoads"));
     const Function& function =
         Function::Handle(isolate,
                          corelib.LookupFunctionAllowPrivate(function_name));
     ASSERT(!function.IsNull());
     const Array& args = Array::empty_array();
@@ skipping 92 matching lines @@
 
 
 DART_EXPORT void Dart_RegisterRootServiceRequestCallback(
     const char* name,
     Dart_ServiceRequestCallback callback,
     void* user_data) {
   Service::RegisterRootEmbedderCallback(name, callback, user_data);
 }
 
 }  // namespace dart