b=922458 allow copying the last sample in an AudioBuffer channel r=ehsan

--HG--
extra : transplant_source : %5EM%40g%06n%04%A1%DB%0A%7D%3A%5C6%21%CA%C101%09
b=923591 don't warn when checkLoadURIStrWithPrincipal() returns NS_ERROR_DOM_BAD_URI r=bz

--HG--
extra : transplant_source : J%09t%A3Z%B4%8C%B9%99%E0O%CE3%7Ex%93vu%9BA
b=924286 handle non-unit mVolume in BiquadFilterNode r=ehsan

--HG--
extra : transplant_source : %E5%9E%3E%5D%F2%E5%99%7B%88%DB%21%7D%1C%82%1A.q%26%F0%EA
b=924288 no need to set filter parameters after every process() r=ehsan

--HG--
extra : transplant_source : %23%D1%3B%D8%03%85%25%95%A8z%15%24K%F0%F7f2%20u%95