simplified code to be compatible with node 4

lib/process/master.js

@@ -59,22 +59,12 @@ process.on('message', function(msg) {
   }
 });
 
-var jobHandler = {
-  get: function(target, name) {
-    if(name === 'progress'){
-      return function(progress){
-        process.send({
-          cmd: 'progress',
-          value: progress
-        });
-      };
-    }else{
-      return target[name];
-    }
-  }
-};
-
 function wrapJob(job){
-  var proxy = new Proxy(job, jobHandler);
-  return proxy;
+  job.progress = function(progress){
+    process.send({
+      cmd: 'progress',
+      value: progress
+    });
+  };
+  return job;
 }