warn(SyntheticEvent): Update tests to check for throwing when accessi…

…ng properties on a destructored syntheticEvent

src/renderers/dom/client/syntheticEvents/__tests__/SyntheticEvent-test.js

@@ -72,13 +72,13 @@ describe('SyntheticEvent', function() {
     expect(syntheticEvent.isPersistent()).toBe(true);
   });
 
-  it('should be nullified if the synthetic event has called destructor', function() {
+  it('should throw an error when trying to access properties if the synthetic event has called destructor', function() {
     var target = document.createElement('div');
     var syntheticEvent = createEvent({srcElement: target});
     syntheticEvent.destructor();
-    expect(syntheticEvent.type).toBe(null);
-    expect(syntheticEvent.nativeEvent).toBe(null);
-    expect(syntheticEvent.target).toBe(null);
+    expect(() => syntheticEvent.type).toThrow();
+    expect(() => syntheticEvent.nativeEvent).toThrow();
+    expect(() => syntheticEvent.target).toThrow();
   });
 
   it('should warn if the synthetic event has been released when calling `preventDefault`', function() {