Apply 2d transforms when static

## Problem

Safari doesn't handle 3d transforms properly, so we need to apply 2d
transforms in order to get Safari to un-blur zoomed SVG.

## Solution

Apply an equivalent 2d transform at the end of certain interaction events to force the browser to un-blur.

## Tests

Added.

## QA / +10

Check out the branch, rebower. Tests should pass, run them in Chrome and Safari as well as CLI. Open the scroll list demo, move around, zoom in, etc. In the DOM inspector you should see that 3d transforms are applied during movement and are reverted to 2d transforms when the movement ends.