Ensure isolates have a root library so createMirrorSystem() and spawnUri() are happy.

sky/engine/core/script/dart_controller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sky/engine/config.h"
 #include "sky/engine/core/script/dart_controller.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 186 matching lines @@
       kDartIsolateSnapshotBuffer, dart_state, error);
   CHECK(isolate) << error;
   dart_state->set_isolate(isolate);
 
   CHECK(!LogIfError(Dart_SetLibraryTagHandler(LibraryTagHandler)));
 
   {
     DartApiScope apiScope;
     Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
     Builtin::SetNativeResolver(Builtin::kMojoInternalLibrary);
+
+    // Ensure the isolate has a root library.
+    Dart_LoadScript(Dart_NewStringFromCString("dart:empty"),
+                    Dart_NewStringFromCString(""), 0, 0);
   }
 
   Dart_ExitIsolate();
 
   CHECK(Dart_IsolateMakeRunnable(isolate));
   return isolate;
 }
 
 static void CallHandleMessage(base::WeakPtr<DartState> dart_state) {
   TRACE_EVENT0("sky", "CallHandleMessage");
@@ skipping 49 matching lines @@
       static_cast<DartState*>(dom_dart_state_.get()), &error);
   Dart_SetMessageNotifyCallback(MessageNotifyCallback);
   CHECK(isolate) << error;
   dom_dart_state_->set_isolate(isolate);
   Dart_SetGcCallbacks(DartGCPrologue, DartGCEpilogue);
   CHECK(!LogIfError(Dart_SetLibraryTagHandler(LibraryTagHandler)));
 
   {
     DartApiScope apiScope;
 
+    // Ensure the isolate has a root library.
+    Dart_LoadScript(Dart_NewStringFromCString("dart:empty"),
+                    Dart_NewStringFromCString(""), 0, 0);
+
     Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
     Builtin::SetNativeResolver(Builtin::kMojoInternalLibrary);
     BuiltinNatives::Init();
 
     builtin_sky_ = adoptPtr(new BuiltinSky(dart_state()));
     dart_state()->class_library().set_provider(builtin_sky_.get());
     builtin_sky_->InstallWindow(dart_state());
 
     document->frame()->loaderClient()->didCreateIsolate(isolate);
 
@@ skipping 21 matching lines @@
   CHECK(Dart_SetVMFlags(argc, argv));
   CHECK(Dart_Initialize(kDartVmIsolateSnapshotBuffer,
                         IsolateCreateCallback,
                         nullptr,  // Isolate interrupt callback.
                         UnhandledExceptionCallback, IsolateShutdownCallback,
                         // File IO callbacks.
                         nullptr, nullptr, nullptr, nullptr, nullptr));
 }
 
 } // namespace blink