improve: add compatibility with the vintageous plugin

Hi, fixed the wrong code of deleting `view_is_widget(view)`

Currently `SublimeBlockCursor` can't work properly with the new `Vintageous` plugin, the block doesn't disappear when entering insert mode, this pull request fixs this.

BTW I'm using ST3 so I had to use @sergeylunev's code to make sure this works.

Hope you don't mind @sergeylunev