Fix zoomable on some mobile devices
Fix zoomable on some mobile devices

Summary:
Since we're not using aphrodite for these inline styles,
we have to auto-prefix ourselves or Android <= 4.4 and
iOS < 9.2 won't work properly.

I debated using aphrodite here, but the dynamic nature
of the rules would mean many styles are injected into
the page, which seemed unnecessary overhead?

Test Plan:
 - run an Android emulator running 4.4 or lower
 - use hack in https://phabricator.khanacademy.org/D27800 to point device to
 local webapp
 - run webapp with this change
 - open "Trends in categorical data" - that exercise always has tables
 - make sure the tables zoom!

Reviewers: kevinb, charlie

Reviewed By: kevinb, charlie

Subscribers: jared

Differential Revision: https://phabricator.khanacademy.org/D27817

ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus,ariabuckles/perseus,learningequality/perseus,ariabuckles/perseus