Normative: TypedArray.prototype.sort: comparefn must be fn or undef…

…ined

This requires implementations throw a `TypeError` when the compare
function is neither undefined nor a function, which is currently vaguely
implied but not explicitly required.

spec.html

@@ -32671,6 +32671,7 @@ <h1>%TypedArray%.prototype.sort ( _comparefn_ )</h1>
         <p>This function is not generic. The *this* value must be an object with a [[TypedArrayName]] internal slot.</p>
         <p>Upon entry, the following steps are performed to initialize evaluation of the `sort` function. These steps are used instead of the entry steps in <emu-xref href="#sec-array.prototype.sort"></emu-xref>:</p>
         <emu-alg>
+          1. If _comparefn_ is not *undefined* and IsCallable(_comparefn_) is *false*, throw a *TypeError* exception.
           1. Let _obj_ be the *this* value.
           1. Let _buffer_ be ? ValidateTypedArray(_obj_).
           1. Let _len_ be _obj_.[[ArrayLength]].