cleanup

- use prototype-less objects where feasible (minor speed improvement)
- get rid of HOP

lib/compress.js

@@ -1449,7 +1449,7 @@ merge(Compressor.prototype, {
     OPT(AST_SymbolRef, function(self, compressor){
         if (self.undeclared()) {
             var defines = compressor.option("global_defs");
-            if (defines && HOP(defines, self.name)) {
+            if (defines && defines.hasOwnProperty(self.name)) {
                 return make_node_from_constant(compressor, defines[self.name], self);
             }
             switch (self.name) {