http: support old private properties and function

PR-URL: nodejs#10941
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/_http_outgoing.js

@@ -83,6 +83,75 @@ function OutgoingMessage() {
 util.inherits(OutgoingMessage, Stream);
 
 
+Object.defineProperty(OutgoingMessage.prototype, '_headers', {
+  get: function() {
+    return this.getHeaders();
+  },
+  set: function(val) {
+    if (val == null) {
+      this[outHeadersKey] = null;
+    } else if (typeof val === 'object') {
+      const headers = this[outHeadersKey] = {};
+      const keys = Object.keys(val);
+      for (var i = 0; i < keys.length; ++i) {
+        const name = keys[i];
+        headers[name.toLowerCase()] = [name, val[name]];
+      }
+    }
+  }
+});
+
+Object.defineProperty(OutgoingMessage.prototype, '_headerNames', {
+  get: function() {
+    const headers = this[outHeadersKey];
+    if (headers) {
+      const out = new StorageObject();
+      const keys = Object.keys(headers);
+      for (var i = 0; i < keys.length; ++i) {
+        const key = keys[i];
+        const val = headers[key][0];
+        out[key] = val;
+      }
+      return out;
+    } else {
+      return headers;
+    }
+  },
+  set: function(val) {
+    if (typeof val === 'object' && val !== null) {
+      const headers = this[outHeadersKey];
+      if (!headers)
+        return;
+      const keys = Object.keys(val);
+      for (var i = 0; i < keys.length; ++i) {
+        const header = headers[keys[i]];
+        if (header)
+          header[0] = val[keys[i]];
+      }
+    }
+  }
+});
+
+
+OutgoingMessage.prototype._renderHeaders = function _renderHeaders() {
+  if (this._header) {
+    throw new Error('Can\'t render headers after they are sent to the client');
+  }
+
+  var headersMap = this[outHeadersKey];
+  if (!headersMap) return {};
+
+  var headers = {};
+  var keys = Object.keys(headersMap);
+
+  for (var i = 0, l = keys.length; i < l; i++) {
+    var key = keys[i];
+    headers[headersMap[key][0]] = headersMap[key][1];
+  }
+  return headers;
+};
+
+
 exports.OutgoingMessage = OutgoingMessage;