False negative for PBKDF2+deriveKey

[wiml]

On my browser (FF 61.0.2 on macOS) the PBKDF2+deriveKey() square is marked N/A, with the tooltip AESCBC is not defined, even though I can actually use PBKDF2+deriveKey() on this browser. Looking at the source code, it seems like the problem is that the AESCBC variable is defined after many of the places that use it, but this only causes a failure when the relevant promises resolve quickly enough.