Bug 905141 - Increase fuzziness of some WebGL reftests on B2G - no review, bustage fix

These were already marked as fuzzy on B2G for 83 pixels. With the B2G emulator BGRA patch now deployed on the test slaves, it appears from reftests logs that the fuzziness needs to be updated from 83 pixels to 90 or 91 pixels depending on the test.