Clean up some redundant or otherwise suspect code

* java/org/gnu/emacs/EmacsOpenActivity.java (onCreate):
Don't check if URI is non-NULL, for instanceof checks this
also.

* java/org/gnu/emacs/EmacsSafThread.java (accessDocument1):
Don't check !writable twice.

* java/org/gnu/emacs/EmacsService.java (documentIdFromName):
Designate this function as public, since it is called
through JNI.

java/org/gnu/emacs/EmacsService.java

@@ -1413,7 +1413,7 @@ public final class EmacsService extends Service
      of OperationCanceledException, SecurityException,
      FileNotFoundException, or UnsupportedOperationException.  */
 
-  private int
+  public int
   documentIdFromName (String tree_uri, String name, String[] id_return)
   {
     /* Start the thread used to run SAF requests if it isn't already