Adjust iOS frame start times to match the platform info (#11802)

shell/platform/darwin/ios/framework/Source/vsync_waiter_ios.mm

@@ -114,7 +114,8 @@ float VsyncWaiterIOS::GetDisplayRefreshRate() const {
 }
 
 - (void)onDisplayLink:(CADisplayLink*)link {
-  fml::TimePoint frame_start_time = fml::TimePoint::Now();
+  CFTimeInterval delay = CACurrentMediaTime() - link.timestamp;
+  fml::TimePoint frame_start_time = fml::TimePoint::Now() - fml::TimeDelta::FromSecondsF(delay);
   fml::TimePoint frame_target_time = frame_start_time + fml::TimeDelta::FromSecondsF(link.duration);
 
   display_link_.get().paused = YES;