Fix DevMode server (jetty) restart

The wac.start() call was failing with
java.util.concurrent.RejectedExecutionException because the server
wasn't started. While switching the wac.start() and server.start()
calls work, actually only one of them is needed.
server.stop() / server.start() was added to workaround permgen
exhaustion, so let's keep those, which will cascade into stopping
and restarting the webapp.

Change-Id: Ia345c29b477f1ffed82e4f14013b8f3773acdc05
diff --git a/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java b/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
index 317159c..f990610 100644
--- a/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
+++ b/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
@@ -293,9 +293,7 @@
       // Temporarily log Jetty on the branch.
       Log.setLog(new JettyTreeLogger(branch));
       try {
-        wac.stop();
         server.stop();
-        wac.start();
         server.start();
         branch.log(TreeLogger.INFO, "Reload completed successfully");
       } catch (Exception e) {