Cleanup a couple unused variables

src/core/__tests__/ReactMockedComponent-test.js

@@ -15,7 +15,6 @@ var React;
 var ReactComponent;
 var ReactTestUtils;
 
-var reactComponentExpect;
 var mocks;
 
 var OriginalComponent;

src/core/instantiateReactComponent.js

@@ -14,7 +14,6 @@
 
 var warning = require('warning');
 
-var ReactElement = require('ReactElement');
 var ReactNativeComponent = require('ReactNativeComponent');
 
 // This is temporary until we've hidden all the implementation details