[fix] Fix the enumerability of some properties

Make the `CONNECTING`, `OPEN`, `CLOSING`, `CLOSED`, `binaryType`,
`bufferedAmount`, `extensions`, `onclose`, `onerror`, `onmessage`,
`onopen`, `protocol`, `readyState`, and `url` properties enumerable.

lib/websocket.js

@@ -74,19 +74,6 @@ class WebSocket extends EventEmitter {
     }
   }
 
-  get CONNECTING() {
-    return WebSocket.CONNECTING;
-  }
-  get CLOSING() {
-    return WebSocket.CLOSING;
-  }
-  get CLOSED() {
-    return WebSocket.CLOSED;
-  }
-  get OPEN() {
-    return WebSocket.OPEN;
-  }
-
   /**
    * This deviates from the WHATWG interface since ws doesn't support the
    * required default "blob" type (instead we define a custom "nodebuffer"
@@ -394,10 +381,21 @@ class WebSocket extends EventEmitter {
 }
 
 readyStates.forEach((readyState, i) => {
-  Object.defineProperty(WebSocket, readyState, {
-    enumerable: true,
-    value: i
-  });
+  const descriptor = { enumerable: true, value: i };
+
+  Object.defineProperty(WebSocket.prototype, readyState, descriptor);
+  Object.defineProperty(WebSocket, readyState, descriptor);
+});
+
+[
+  'binaryType',
+  'bufferedAmount',
+  'extensions',
+  'protocol',
+  'readyState',
+  'url'
+].forEach((property) => {
+  Object.defineProperty(WebSocket.prototype, property, { enumerable: true });
 });
 
 //
@@ -406,6 +404,8 @@ readyStates.forEach((readyState, i) => {
 //
 ['open', 'error', 'close', 'message'].forEach((method) => {
   Object.defineProperty(WebSocket.prototype, `on${method}`, {
+    configurable: true,
+    enumerable: true,
     /**
      * Return the listener of the event.
      *