It looks like some changes were made in bug 23737.
A few instances of "SpeechSynthesisVoiceList" remain. In the IDL it should be "sequence getVoices()" and in the prose it needs to say things about the sequence of SpeechSynthesisVoice objects instead.
Moved from https://www.w3.org/Bugs/Public/show_bug.cgi?id=30009: