minor readability / refactors

I have been hacking at this test trying to understand why the N5 is
still sometimes crashy (it seems, less but not zero now). No luck so far.

But, while I've been reading and hacking at it, I think I've made a
few small improvements, mostly to readability.

BUG=skia:

Review URL: https://codereview.chromium.org/870803002
1 file changed