Speedscope crashes when at zoom > 100% in Arc

[jlfwong]

Haven't diagnosed why this happens yet

Seems to cause a crash:

speedscope.80eb88d2.js:14 Uncaught RangeError: Maximum call stack size exceeded
    at get renderTargetWidthInPixels (speedscope.80eb88d2.js:14:5608)
    at speedscope.80eb88d2.js:30:516
    at speedscope.80eb88d2.js:14:6435
    at Set.forEach (<anonymous>)
    at a.resize (speedscope.80eb88d2.js:14:6424)
    at speedscope.80eb88d2.js:183:2230
    at speedscope.80eb88d2.js:30:725
    at speedscope.80eb88d2.js:14:6435
    at Set.forEach (<anonymous>)
    at a.resize (speedscope.80eb88d2.js:14:6424)