Created test for no-op history state operations.

ios/web/test/web_int_test.h

Index: ios/web/test/web_int_test.h
diff --git a/ios/web/test/web_int_test.h b/ios/web/test/web_int_test.h
index 8544c257460a6fe164c4216b191e310615f7ac33..71ff8d2bdeac29b9f070f413d11ca03af6b1cccf 100644
--- a/ios/web/test/web_int_test.h
+++ b/ios/web/test/web_int_test.h
@@ -34,6 +34,11 @@ class WebIntTest : public WebTest {
     return web_state()->GetNavigationManager();
   }
 
+  // Returns the last committed NavigationItem in |navigation_manager|.
+  NavigationItem* GetLastCommittedItem() {
+    return navigation_manager()->GetLastCommittedItem();
+  }
+
   // Synchronously executes |script| on |web_state|'s JS injection receiver and
   // returns the result.
   id ExecuteJavaScript(NSString* script);