Disable one irrelevant test for Fiber

We don't use transaction objects.

scripts/fiber/tests-failing.txt

@@ -132,7 +132,6 @@ src/renderers/shared/stack/reconciler/__tests__/ReactStatelessComponent-test.js
 * should warn when using non-React functions in JSX
 
 src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js
-* should share reconcile transaction across different roots
 * should queue mount-ready handlers across different roots
 * should queue updates from during mount
 * marks top-level updates

scripts/fiber/tests-passing.txt

@@ -1431,6 +1431,7 @@ src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js
 * should update children even if parent blocks updates
 * should not reconcile children passed via props
 * should flow updates correctly
+* should share reconcile transaction across different roots
 * should flush updates in the correct order
 * should flush updates in the correct order across roots
 * should queue nested updates

src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js

@@ -13,6 +13,7 @@
 
 var React;
 var ReactDOM;
+var ReactDOMFeatureFlags;
 var ReactTestUtils;
 var ReactUpdates;
 
@@ -20,6 +21,7 @@ describe('ReactUpdates', () => {
   beforeEach(() => {
     React = require('React');
     ReactDOM = require('ReactDOM');
+    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactTestUtils = require('ReactTestUtils');
     ReactUpdates = require('ReactUpdates');
   });
@@ -506,6 +508,9 @@ describe('ReactUpdates', () => {
   });
 
   it('should share reconcile transaction across different roots', () => {
+    if (ReactDOMFeatureFlags.useFiber) {
+      return;
+    }
     var ReconcileTransaction = ReactUpdates.ReactReconcileTransaction;
     spyOn(ReconcileTransaction, 'getPooled').and.callThrough();