[Fiber] Add tests for scheduling inside callbacks (#8186)

* Add tests for scheduling inside callbacks

* Don't test implementation details

scripts/fiber/tests-passing.txt

@@ -819,6 +819,18 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
 * splits deferred work on multiple roots
 * works on deferred roots in the order they were scheduled
 * handles interleaved deferred and animation work
+* performs animation work in animation callback
+* schedules deferred work in animation callback
+* schedules deferred work and performs animation work in animation callback
+* performs animation work and schedules deferred work in animation callback
+* performs deferred work in deferred callback if it has time
+* schedules deferred work in deferred callback if it runs out of time
+* performs animated work in deferred callback if it has time
+* performs animated work and deferred work in deferred callback if it has time
+* performs deferred and animated work work in deferred callback if it has time
+* FIXME: schedules animated work as if it was deferred in deferred callback if it runs out of time
+* schedules animated work and deferred work in deferred callback if it runs out of time
+* schedules deferred work and animated work in deferred callback if it runs out of time
 
 src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * can update child nodes of a host instance

src/renderers/noop/ReactNoop.js

@@ -172,14 +172,6 @@ var ReactNoop = {
     }
   },
 
-  hasScheduledDeferredCallback() {
-    return Boolean(scheduledDeferredCallback);
-  },
-
-  hasScheduledAnimationCallback() {
-    return Boolean(scheduledAnimationCallback);
-  },
-
   // Shortcut for testing a single root
   render(element : ReactElement<any>, callback: ?Function) {
     ReactNoop.renderToRootWithID(element, DEFAULT_ROOT_ID, callback);