[gui] JNodeActions not working when called from context menu

[CmP-lt]

Since 0c3afcc all actions that extend JNodeAction don't work (as if their runAction method doesn't get called, which may be the case) when they are called from context menu, but work normally when called with bound key. This issue doesn't affect actions that extend AbstractAction directly (like CommentAction and CommentSearchAction), they work normally both from context menu and with bound key.

[skylot]

@CmP-lt thank you for the tip!
It is weird that method popupMenuWillBecomeInvisible called before actionPerformed. Yeah, docs mention Note that a JPopupMenu can become invisible any time but I didn't think this can be before the reason of menu closing 😕
I commit a fix which don't reset current node in popupMenuWillBecomeInvisible method.
Also looks like this fix resolves a #1514.