Call evt.preventDefault() on native click event except for INPUT controls.  This prevents the double click problem while still allowing keyboard to popup on android.   Also, forward clicks on labels to be clicks on the associated nodes.   Patch from Eric Durocher (IBM, CCLA).  Refs #15878 !strict.

Also removing "target" property to on.emit() hash, since it's already specified as the first argument to on.emit().

Finally, add CSS to avoid flash when clicking Tree.