Keep rects local for link hints.
Keep rects local for link hints.

Previously, we passed each hints rect to every other frame.  However,
the rect is only actually needed in its own frame.

Here, we instead keep (and use) each hint's rect locally only.

mrmr1993/vimium,poacher2k/vimium,decaffeinate-examples/vimium,gdh1995/vimium,philc/vimium,smblott-github/vimium,philc/vimium,mrmr1993/vimium,poacher2k/vimium,decaffeinate-examples/vimium,smblott-github/vimium,poacher2k/vimium,gdh1995/vimium,gdh1995/vimium,willsALMANJ/vimium,willsALMANJ/vimium,smblott-github/vimium,mrmr1993/vimium,philc/vimium,decaffeinate-examples/vimium,willsALMANJ/vimium