Editorial: Fix casing of @@hasInstance well-known symbol (#1978)

spec.html

@@ -15009,7 +15009,7 @@ <h1>Runtime Semantics: Evaluation</h1>
 
     <emu-clause id="sec-instanceofoperator" aoid="InstanceofOperator">
       <h1>Runtime Semantics: InstanceofOperator ( _V_, _target_ )</h1>
-      <p>The abstract operation InstanceofOperator(_V_, _target_) implements the generic algorithm for determining if  ECMAScript value _V_ is an instance of object _target_ either by consulting _target_'s @@hasinstance method or, if absent, determining whether the value of _target_'s *"prototype"* property is present in _V_'s prototype chain. This abstract operation performs the following steps:</p>
+      <p>The abstract operation InstanceofOperator(_V_, _target_) implements the generic algorithm for determining if  ECMAScript value _V_ is an instance of object _target_ either by consulting _target_'s @@hasInstance method or, if absent, determining whether the value of _target_'s *"prototype"* property is present in _V_'s prototype chain. This abstract operation performs the following steps:</p>
       <emu-alg>
         1. If Type(_target_) is not Object, throw a *TypeError* exception.
         1. Let _instOfHandler_ be ? GetMethod(_target_, @@hasInstance).