Use directExecutor().

Guava 18 deprecated sameThreadExecutor() and split
the use case into two options:
newDirectExecutorService() and directExecutor().
Use directExecutor() as we don't need
ExecutorService#shutdown semantics and this
has a positive performance impact.

Signed-off-by: Luke Inman-Semerau <luke.semerau@gmail.com>

java/client/src/org/openqa/selenium/safari/WebSocketConnection.java

@@ -136,7 +136,7 @@ public ListenableFuture<String> send(String data) {
       public void run() {
         pendingResponse.compareAndSet(response, null);
       }
-    }, MoreExecutors.sameThreadExecutor());
+    }, MoreExecutors.directExecutor());
 
     if (pendingResponse.compareAndSet(null, response)) {
       TextWebSocketFrame frame = new TextWebSocketFrame(data);