 - decidePolicyForNavigationAction
<NSURLRequest URL about:blank, main document URL subframe-click-target-top.html, http method GET> is main frame - no should open URLs externally - no
 - decidePolicyForNavigationAction
<NSURLRequest URL resources/iframe-click-notify-done-target-top.html, main document URL subframe-click-target-top.html, http method GET> is main frame - no should open URLs externally - no
 - decidePolicyForNavigationAction
<NSURLRequest URL resources/notify-done.html, main document URL resources/notify-done.html, http method GET> is main frame - yes should open URLs externally - yes