Add performance.now() to the d8 shell.

src/d8.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 148 matching lines @@
 i::OS::MemoryMappedFile* Shell::counters_file_ = NULL;
 CounterCollection Shell::local_counters_;
 CounterCollection* Shell::counters_ = &local_counters_;
 i::Mutex Shell::context_mutex_;
 Persistent<Context> Shell::utility_context_;
 #endif  // V8_SHARED
 
 Persistent<Context> Shell::evaluation_context_;
 ShellOptions Shell::options;
 const char* Shell::kPrompt = "d8> ";
+const i::TimeTicks Shell::kInitialTicks = i::TimeTicks::HighResolutionNow();
 
 
 const int MB = 1024 * 1024;
 
 
 #ifndef V8_SHARED
 bool CounterMap::Match(void* key1, void* key2) {
   const char* name1 = reinterpret_cast<const char*>(key1);
   const char* name2 = reinterpret_cast<const char*>(key2);
   return strcmp(name1, name2) == 0;
@@ skipping 103 matching lines @@
 
 
 int PerIsolateData::RealmFind(Handle<Context> context) {
   for (int i = 0; i < realm_count_; ++i) {
     if (realms_[i] == context) return i;
   }
   return -1;
 }
 
 
+// window.performance.now() returns a time stamp as double, measured in
+// milliseconds.
+void Shell::WindowPerformanceNow(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  i::TimeDelta delta = i::TimeTicks::HighResolutionNow() - kInitialTicks;
+  args.GetReturnValue().Set(delta.InMillisecondsF());
+}
+
+
 // Realm.current() returns the index of the currently active realm.
 void Shell::RealmCurrent(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Isolate* isolate = args.GetIsolate();
   PerIsolateData* data = PerIsolateData::Get(isolate);
   int index = data->RealmFind(isolate->GetEnteredContext());
   if (index == -1) return;
   args.GetReturnValue().Set(index);
 }
 
 
@@ skipping 563 matching lines @@
   realm_template->Set(String::New("dispose"),
                       FunctionTemplate::New(RealmDispose));
   realm_template->Set(String::New("switch"),
                       FunctionTemplate::New(RealmSwitch));
   realm_template->Set(String::New("eval"),
                       FunctionTemplate::New(RealmEval));
   realm_template->SetAccessor(String::New("shared"),
                               RealmSharedGet, RealmSharedSet);
   global_template->Set(String::New("Realm"), realm_template);
 
+  Handle<ObjectTemplate> window_template = ObjectTemplate::New();
+  Handle<ObjectTemplate> performance_template = ObjectTemplate::New();
+  performance_template->Set(String::New("now"),
+                            FunctionTemplate::New(WindowPerformanceNow));
+  window_template->Set(String::New("performance"), performance_template);
+  global_template->Set(String::New("window"), window_template);
+
 #if !defined(V8_SHARED) && !defined(_WIN32) && !defined(_WIN64)
   Handle<ObjectTemplate> os_templ = ObjectTemplate::New();
   AddOSMethods(os_templ);
   global_template->Set(String::New("os"), os_templ);
 #endif  // V8_SHARED
 
   return global_template;
 }
 
 
@@ skipping 853 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif