Fixing Dolfin2 problem with touchmove event

[waldbaerkoch]

Samsung's Dolfin 2 browser has a problem with touchmove events: clientY seems to be increased by the difference between pageY and clientY at touchstart. I triy to workaround this problem by addiing

var _isDolfin2 = (/Dolfin\/2\./).test(navigator.userAgent);

in the outermost closure,

var _diffY;

in the FTScroller constructor,

_diffY = _isDolfin2 ? touchEvent.pageY - touchEvent.clientY : 0;

at the end of _onTouchStart,

 _updateScroll(touchEvent.clientX, touchEvent.clientY - _diffY, moveEvent.timeStamp, moveEvent);

instead of

_updateScroll(touchEvent.clientX, touchEvent.clientY, moveEvent.timeStamp, moveEvent);

in _onTouchMove, and

_diffY = 0;

at the end of _onTouchEnd.

[rowanbeentje]

Hacky but very sensible :) Thanks for taking the time to debug this one - I need a little time to replicate this just to play around with the fix, but this'll probably be merged exactly as you suggest.