456209 - Bad ContextClassLoader in WebSocket onMessage

+ Sets the class loader on an incoming frame to the
  class loader that loaded the web socket session

Also-by: Michael MacFadden <michael@macfadden.org>
Signed-off-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/WebSocketSession.java

@@ -303,10 +303,19 @@ public class WebSocketSession extends ContainerLifeCycle implements Session, Inc
     @Override
     public void incomingFrame(Frame frame)
     {
-        if (connection.getIOState().isInputAvailable())
+        ClassLoader old = Thread.currentThread().getContextClassLoader();
+        try
         {
-            // Forward Frames Through Extension List
-            incomingHandler.incomingFrame(frame);
+            Thread.currentThread().setContextClassLoader(classLoader);
+            if (connection.getIOState().isInputAvailable())
+            {
+                // Forward Frames Through Extension List
+                incomingHandler.incomingFrame(frame);
+            }
+        }
+        finally
+        {
+            Thread.currentThread().setContextClassLoader(old);
         }
     }