Fix 'invoke mapState every time props are changed if it has a second …

…argument'

There are only three prop changes.

1. Initial render
2. outerComponent.setFoo('BAR')
3. outerComponent.setFoo('BAZ')

Did I miss something?

test/components/connect.spec.js

@@ -490,7 +490,7 @@ describe('React', () => {
       outerComponent.setFoo('BAR');
       outerComponent.setFoo('BAZ');
 
-      expect(invocationCount).toEqual(4);
+      expect(invocationCount).toEqual(3);
       expect(propsPassedIn).toEqual({
         foo: 'BAZ'
       });