Fix bug on hashchange event.
Fix bug on hashchange event.

This handler is undefined at the point that it is installed.  The
definition is at the bottom of the file.

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