feat: use monotonic time for performance object

Author: edusperoni

Diff for: NativeScript/runtime/Runtime.h

@@ -77,6 +77,8 @@ class Runtime {
   std::unique_ptr<ModuleInternal> moduleInternal_;
   int workerId_;
   CFRunLoopRef runtimeLoop_;
+  double startTime;
+  double realtimeOrigin;
   // TODO: refactor this. This is only needed because, during program
   // termination (UIApplicationMain not called) the Cache::Workers is released
   // (static initialization order fiasco

Diff for: NativeScript/runtime/Runtime.mm

@@ -154,6 +154,9 @@ void DisposeIsolateWhenPossible(Isolate* isolate) {
     v8Initialized_ = true;
   }
 
+  startTime = platform_->MonotonicallyIncreasingTime();
+  realtimeOrigin = platform_->CurrentClockTimeMillis();
+
   // auto version = v8::V8::GetVersion();
 
   Isolate::CreateParams create_params;
@@ -389,16 +392,17 @@ void DisposeIsolateWhenPossible(Isolate* isolate) {
   Local<FunctionTemplate> nowFuncTemplate = FunctionTemplate::New(isolate, PerformanceNowCallback);
   performanceTemplate->Set(tns::ToV8String(isolate, "now"), nowFuncTemplate);
 
+  performanceTemplate->Set(tns::ToV8String(isolate, "timeOrigin"),
+                           v8::Number::New(isolate, realtimeOrigin));
+
   Local<v8::String> performancePropertyName = ToV8String(isolate, "performance");
   globalTemplate->Set(performancePropertyName, performanceTemplate);
 }
 
 void Runtime::PerformanceNowCallback(const FunctionCallbackInfo<Value>& args) {
-  std::chrono::system_clock::time_point now = std::chrono::system_clock::now();
-  std::chrono::milliseconds timestampMs =
-      std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch());
-  double result = timestampMs.count();
-  args.GetReturnValue().Set(result);
+  auto runtime = Runtime::GetRuntime(args.GetIsolate());
+  args.GetReturnValue().Set(
+      (runtime->platform_->MonotonicallyIncreasingTime() - runtime->startTime) * 1000.0);
 }
 
 void Runtime::DefineNativeScriptVersion(Isolate* isolate, Local<ObjectTemplate> globalTemplate) {