Properly escape attributes in test results

Quotes were not escaped in attributes, which lead to errors as in this result:
http://parsoid.wmflabs.org:8001/result/804ead03252b9694f146b1027b8b5a55d67b4450/hewiki/%D7%A0%D7%A0%D7%95%D7%98%D7%9B%D7%A0%D7%95%D7%9C%D7%95%D7%92%D7%99%D7%99%D7%AA_%D7%93%D7%A0%22%D7%90

Change-Id: I313e803892285e7aa382cc53bd0af5e6a455617b