hashchange: Remove is_exit_overlay code.
hashchange: Remove is_exit_overlay code.

Just calling update_browser_history is sufficient
here, and we end up short-circuiting some code
in hashchanged():

    * we don't need to set state.old_hash, because
      that's what update_browser_history does
    * we bypass the is_overlay_check, which is always
      false in this context

showell/zulip,rishig/zulip,rht/zulip,rht/zulip,eeshangarg/zulip,brainwane/zulip,eeshangarg/zulip,dhcrzf/zulip,zulip/zulip,tommyip/zulip,brainwane/zulip,kou/zulip,zulip/zulip,jackrzhang/zulip,timabbott/zulip,brainwane/zulip,eeshangarg/zulip,rht/zulip,brainwane/zulip,shubhamdhama/zulip,zulip/zulip,synicalsyntax/zulip,shubhamdhama/zulip,rht/zulip,rishig/zulip,andersk/zulip,rht/zulip,timabbott/zulip,brainwane/zulip,synicalsyntax/zulip,eeshangarg/zulip,dhcrzf/zulip,hackerkid/zulip,jackrzhang/zulip,rishig/zulip,punchagan/zulip,tommyip/zulip,punchagan/zulip,eeshangarg/zulip,shubhamdhama/zulip,synicalsyntax/zulip,shubhamdhama/zulip,timabbott/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,synicalsyntax/zulip,shubhamdhama/zulip,punchagan/zulip,showell/zulip,brainwane/zulip,jackrzhang/zulip,eeshangarg/zulip,kou/zulip,hackerkid/zulip,zulip/zulip,dhcrzf/zulip,rishig/zulip,dhcrzf/zulip,tommyip/zulip,andersk/zulip,zulip/zulip,timabbott/zulip,dhcrzf/zulip,synicalsyntax/zulip,hackerkid/zulip,showell/zulip,synicalsyntax/zulip,shubhamdhama/zulip,kou/zulip,punchagan/zulip,zulip/zulip,tommyip/zulip,shubhamdhama/zulip,kou/zulip,jackrzhang/zulip,punchagan/zulip,jackrzhang/zulip,punchagan/zulip,dhcrzf/zulip,andersk/zulip,hackerkid/zulip,tommyip/zulip,hackerkid/zulip,showell/zulip,timabbott/zulip,timabbott/zulip,andersk/zulip,synicalsyntax/zulip,kou/zulip,rishig/zulip,showell/zulip,rishig/zulip,rishig/zulip,andersk/zulip,dhcrzf/zulip,jackrzhang/zulip,rht/zulip,showell/zulip,andersk/zulip,kou/zulip,tommyip/zulip,kou/zulip,hackerkid/zulip,tommyip/zulip,brainwane/zulip,rht/zulip,zulip/zulip,timabbott/zulip,jackrzhang/zulip,eeshangarg/zulip,showell/zulip