Preventing page scroll/zoom when touch dragging on keyboard
Preventing page scroll/zoom when touch dragging on keyboard

Calling `preventDefault()` in the appropriate `touchmove` event
handler should do this, but due to a seeming bug in React this
requires attaching the event handler to the native DOM element,
rather than the usual React way. (See the comment added in the
commit for URLs with more info).

jstrait/jssynth,jstrait/jssynth