switch to GetPrototypeV2()

Should be a noop for us, since we never call GetPrototype() on an
object that would be expected to be the context object

src/workerd/jsg/jsvalue.h

@@ -359,7 +359,7 @@ class JsObject final : public JsBase<v8::Object, JsObject> {
   // Note that when called on a class constructor, this does NOT return `.prototype`, it still
   // returns `.__proto__`. Usefully, though, a class constructor's `__proto__` is always the
   // parent class's constructor.
-  inline JsValue getPrototype() { return JsValue(inner->GetPrototype()); }
+  inline JsValue getPrototype() { return JsValue(inner->GetPrototypeV2()); }
 
   using JsBase<v8::Object, JsObject>::JsBase;