Bug 1467077 - Tab undo changes broke restoreTabs() (#3974)
Bug 1467077 - Tab undo changes broke restoreTabs() (#3974)

restoreTabs() is supposed to create a new tab if there are none,
which I broke in prev commit
Acidburn0zzz/firefox-ios,eoger/firefox-ios,Acidburn0zzz/firefox-ios,HongliYu/firefox-ios,AaronMT/firefox-ios,Acidburn0zzz/firefox-ios,SuPair/firefox-ios,mozilla-mobile/firefox-ios,st3fan/firefox-ios,justindarc/firefox-ios,eoger/firefox-ios,Bunn/firefox-ios,justindarc/firefox-ios,garvankeeley/firefox-ios,mkaply/firefox-ios,StYaphet/firefox-ios,mozilla-mobile/firefox-ios,st3fan/firefox-ios,garvankeeley/firefox-ios,garvankeeley/firefox-ios,garvankeeley/firefox-ios,AaronMT/firefox-ios,SuPair/firefox-ios,mkaply/firefox-ios,flodolo/firefox-ios,StYaphet/firefox-ios,Bunn/firefox-ios,flodolo/firefox-ios,Acidburn0zzz/firefox-ios,eoger/firefox-ios,tecgirl/firefox-ios,eoger/firefox-ios,StYaphet/firefox-ios,mozilla-mobile/firefox-ios,tecgirl/firefox-ios,flodolo/firefox-ios,HongliYu/firefox-ios,mkaply/firefox-ios,st3fan/firefox-ios,Bunn/firefox-ios,Bunn/firefox-ios,AaronMT/firefox-ios,st3fan/firefox-ios,HongliYu/firefox-ios,StYaphet/firefox-ios,garvankeeley/firefox-ios,SuPair/firefox-ios,mozilla-mobile/firefox-ios,garvankeeley/firefox-ios,SuPair/firefox-ios,justindarc/firefox-ios,tecgirl/firefox-ios,flodolo/firefox-ios,tecgirl/firefox-ios,justindarc/firefox-ios,mkaply/firefox-ios,eoger/firefox-ios,st3fan/firefox-ios,mozilla-mobile/firefox-ios,st3fan/firefox-ios,Bunn/firefox-ios,justindarc/firefox-ios,HongliYu/firefox-ios,mozilla-mobile/firefox-ios,HongliYu/firefox-ios,garvankeeley/firefox-ios,st3fan/firefox-ios,HongliYu/firefox-ios,HongliYu/firefox-ios,StYaphet/firefox-ios,flodolo/firefox-ios,StYaphet/firefox-ios,SuPair/firefox-ios,mkaply/firefox-ios,tecgirl/firefox-ios,StYaphet/firefox-ios,tecgirl/firefox-ios,flodolo/firefox-ios,eoger/firefox-ios,eoger/firefox-ios,AaronMT/firefox-ios,mkaply/firefox-ios,Acidburn0zzz/firefox-ios,mkaply/firefox-ios,Bunn/firefox-ios,SuPair/firefox-ios,StYaphet/firefox-ios,justindarc/firefox-ios,SuPair/firefox-ios,Acidburn0zzz/firefox-ios,mozilla-mobile/firefox-ios,tecgirl/firefox-ios,AaronMT/firefox-ios,tecgirl/firefox-ios,AaronMT/firefox-ios,justindarc/firefox-ios,AaronMT/firefox-ios,Acidburn0zzz/firefox-ios,flodolo/firefox-ios,Bunn/firefox-ios,Acidburn0zzz/firefox-ios,st3fan/firefox-ios