A cached PaintHitTestResult to use during a touch sequence. This
is kept so that the renderer doesnβt have to constantly keep making hit tests
while during panning and flinging actions.
This data structure is used to store information about touch events that are
sent from the Renderer to the Constellation, so that they can finish processing
once their DOM events are fired.
The axis of a pan gesture. Once panning begins, the gesture is locked to the
dominant axis for the rest of the sequence, so that e.g. a vertical pan that
passes over a horizontally scrollable element keeps scrolling the page instead
of switching to horizontal scrolling.