 - decidePolicyForNavigationAction 
<NSURLRequest URL resources/user-gesture-target-blank-to-notify-done-from-subframe.html, main document URL resources/user-gesture-target-blank-to-notify-done-from-subframe.html, http method GET> is main frame - yes should open URLs externally - yes
 - decidePolicyForNavigationAction 
<NSURLRequest URL user-gesture-target-blank-to-notify-done.html, main document URL user-gesture-target-blank-to-notify-done-from-subframe.html, http method GET> is main frame - no should open URLs externally - no
 - decidePolicyForNavigationAction 
<NSURLRequest URL notify-done.html, main document URL user-gesture-target-blank-to-notify-done-from-subframe.html, http method GET> is main frame - yes should open URLs externally - yes