ChangeScreen2: Fix click inside of messages

Clicking within a message body should not collapse the message.  It
should have only the default browser behavior.

This is annoyingly obvious if a change message contains a hyperlink
and you click the link.  The message collapses but the link opens in a
new tab.  If the message had another link you also wish to follow, it
is necessary to first re-expand the message.

Move the click listener onto a new <div> that contains only the first
line (aka the header line), which is the natural click target.

Change-Id: Ic3398447df033aa69369c785166ba841f168a83d
(cherry picked from commit cd2fc945ae6ebfc482e4e78c28b781ebff4c9aee)
2 files changed