Add tests for testing forwarding of continuation frames

This adds two tests that send payloads below and at the threshold for continuation frames. Using node 0.12.7 both tests pass. Using node 4.1.2 the test below the threshold passes but the other fails.

test/lib-http-proxy-test.js

@@ -487,6 +487,69 @@ describe('lib/http-proxy.js', function() {
         });
       });
     });
+
+    it('should forward frames with single frame payload (including on node 4.x)', function (done) {
+      var payload = Array(65529).join('0');
+      var ports = { source: gen.port, proxy: gen.port };
+      var proxy = httpProxy.createProxyServer({
+        target: 'ws://127.0.0.1:' + ports.source,
+        ws: true
+      }),
+      proxyServer = proxy.listen(ports.proxy),
+      destiny = new ws.Server({ port: ports.source }, function () {
+        var client = new ws('ws://127.0.0.1:' + ports.proxy);
+
+        client.on('open', function () {
+          client.send(payload);
+        });
+
+        client.on('message', function (msg) {
+          expect(msg).to.be('Hello over websockets');
+          client.close();
+          proxyServer.close();
+          destiny.close();
+          done();
+        });
+      });
+
+      destiny.on('connection', function (socket) {
+        socket.on('message', function (msg) {
+          expect(msg).to.be(payload);
+          socket.send('Hello over websockets');
+        });
+      });
+    });
 
-  })
+    it('should forward continuation frames with big payload (including on node 4.x)', function (done) {
+      var payload = Array(65530).join('0');
+      var ports = { source: gen.port, proxy: gen.port };
+      var proxy = httpProxy.createProxyServer({
+        target: 'ws://127.0.0.1:' + ports.source,
+        ws: true
+      }),
+      proxyServer = proxy.listen(ports.proxy),
+      destiny = new ws.Server({ port: ports.source }, function () {
+        var client = new ws('ws://127.0.0.1:' + ports.proxy);
+
+        client.on('open', function () {
+          client.send(payload);
+        });
+
+        client.on('message', function (msg) {
+          expect(msg).to.be('Hello over websockets');
+          client.close();
+          proxyServer.close();
+          destiny.close();
+          done();
+        });
+      });
+
+      destiny.on('connection', function (socket) {
+        socket.on('message', function (msg) {
+          expect(msg).to.be(payload);
+          socket.send('Hello over websockets');
+        });
+      });
+    });
+  });
 });