LibJS: Pass argument value vectors as const Vector<Value>&

Now that Interpreter keeps all arguments in the CallFrame stack, we can
just pass a const-reference to the CallFrame's argument vector to each
function handler (instead of copying it.)

Libraries/LibJS/Runtime/Function.h

@@ -35,7 +35,7 @@ class Function : public Object {
 public:
     virtual ~Function();
 
-    virtual Value call(Interpreter&, Vector<Value>) = 0;
+    virtual Value call(Interpreter&, const Vector<Value>&) = 0;
 
 protected:
     Function();