Fix evaluating the typeof an arrow function. Using evaluate on used to cause a crash.

lib/compress.js

@@ -738,6 +738,9 @@ merge(Compressor.prototype, {
             // places too. :-( Wish JS had multiple inheritance.
             throw def;
         });
+        def(AST_Arrow, function() {
+            throw def;
+        });
         function ev(node, compressor) {
             if (!compressor) throw new Error("Compressor must be passed");
 
@@ -756,7 +759,8 @@ merge(Compressor.prototype, {
               case "typeof":
                 // Function would be evaluated to an array and so typeof would
                 // incorrectly return 'object'. Hence making is a special case.
-                if (e instanceof AST_Function) return typeof function(){};
+                if (e instanceof AST_Function ||
+                    e instanceof AST_Arrow) return typeof function(){};
 
                 e = ev(e, compressor);