add baseline start and baseline end events

Summary: Adds Baseline start and end events to be handled later for instrumentation

Reviewed By: davidaurelio

Differential Revision: D16048790

fbshipit-source-id: 8409dbb633168753a7bf8fab20bc6551d113ddd6

tests/EventsTest.cpp

@@ -300,6 +300,9 @@ void EventTest::listen(const YGNode& node, Event::Type type, Event::Data data) {
     case Event::MeasureCallbackStart:
     case Event::MeasureCallbackEnd:
       break;
+    case Event::NodeBaselineStart:
+    case Event::NodeBaselineEnd:
+      break;
   }
 }