Test - CookieManagerTests.ShouldClearCookies wait for render to finish

- Wait for render idle instead of navigation, we might still
  need to investigate why the navigation completed on a reload
  isn't allowing JS evaluation

Author: amaitland

CefSharp.Test/CookieManager/CookieManagerTests.cs

@@ -207,7 +207,7 @@ public async Task ShouldClearCookies()
 
             Browser.Reload();
 
-            await Browser.WaitForNavigationAsync();
+            await Browser.WaitForRenderIdleAsync();
 
             response = await Browser.EvaluateScriptAsync<string>("document.cookie");