frontend: performFind was not focusing the next a-element
frontend: performFind was not focusing the next a-element

To reproduce, pre-this-patch:

1 Enter find mode ('/')
2 Search for something that matches multiple a-hrefs on the page
3 'Enter' to indicate that you've found your search term
4 findNext ('n')
  4a Now, the next element get's a highlight but is not focused
5 activate/goto ('enter')
  5a The first found match (3) is triggered

An easy way to reproduce: go to a gitweb page, search for "summary", try
to go to any but the first link's href.

Signed-off-by: Carl Helmertz <d78a787955449ad50f586e5155db5f9260d297a8@gmail.com>

douglas-larocca/vimium,decaffeinate-examples/vimium,jb55/vimium-plus,douglas-larocca/vimium,wildeyes/vimium,Aleroniponi/vimium,poacher2k/vimium,borgified/vimium,tuchangwei/vimium,Aleroniponi/vimium,mrmr1993/vimium,Robinson10240/vimium,PickRelated/vimium,elegantwww/vimium,douglas-larocca/vimium,philc/vimium,VPashkov/vimium,gdh1995/vimium,Robinson10240/vimium,bkudria/vimium,PickRelated/vimium,justalittlenoob/vimium,VPashkov/vimium,elderbas/vimium,zhangmin510/vimium,poacher2k/vimium,crazypenguincode/vimium,borgified/vimium,philc/vimium,hhsue/vimium,Lw-Cui/vimium,willsALMANJ/vimium,tuchangwei/vimium,PickRelated/vimium,Aleroniponi/vimium,Robinson10240/vimium,wildeyes/vimium,cyrixhero/vimium,csmalin/vimium,PrestanceDesign/vimium,Lw-Cui/vimium,tuchangwei/vimium,bkudria/vimium,justalittlenoob/vimium,wildeyes/vimium,hhsue/vimium,dimatter/vimium,smblott-github/vimium,poacher2k/vimium,crazypenguincode/vimium,VPashkov/vimium,smblott-github/vimium-smblott,elderbas/vimium,csmalin/vimium,mrmr1993/vimium,philc/vimium,Lw-Cui/vimium,dimatter/vimium,hhsue/vimium,mrmr1993/vimium,jb55/vimium-plus,zhangmin510/vimium,smblott-github/vimium,willsALMANJ/vimium,dimatter/vimium,gdh1995/vimium,smblott-github/vimium,decaffeinate-examples/vimium,smblott-github/vimium-smblott,elegantwww/vimium,csmalin/vimium,gdh1995/vimium,PrestanceDesign/vimium,bkudria/vimium,zhangmin510/vimium,elegantwww/vimium,cyrixhero/vimium,borgified/vimium,cyrixhero/vimium,PrestanceDesign/vimium,justalittlenoob/vimium,decaffeinate-examples/vimium,elderbas/vimium,willsALMANJ/vimium