6.2.10 EE GA1, 6.2.X EE, 7.0.1 CE GA2
The issue and reproduction steps:
1) Add search portlet on a page
2) Use an iPhone5, iPhone6, or iPad Air2 (Safari) or Macbook Pro : search for anything to get to the search result page
3) Use browser back button to go back to the page
5a) [on iPad] Place cursor into search field and click "open" on the keyboard: Nothing happens but should trigger a search (search button doesn't seem to work either)
5b) [on Macbook Pro] You can modify the search text, but you can not click on the search icon (magnifier). If you hit Enter to start searching, nothing happens.
On master, the search portlet is embedded, and the issue is not reproducible.