Bug 859022 - Remove the MSVC exemption for FAIL_ON_WARNINGS in content/media. r=roc a=bajaj

--HG--
extra : transplant_source : %AE%AE%60%C6%5C%C7f%9C%13%9B%F4%2C%DA%AB%8F%2A%7D%93cb
Backed out changeset 359aa68d311f (bug 859022) for build bustage a=me