2.1.2 [W3C-WEBIDL1] Section 3.10.17 USVString

V0002: The USVString type is not supported

The specification states:

 3.10.17 USVString
 The USVString type corresponds to the set of all possible sequences of Unicode scalar 
 values, which are all of the Unicode code points apart from the surrogate code points.

IE11 Mode, IE10 Mode, and IE9 Mode (All versions)

The USVString type is not supported.