fix some key navigation issues

lib/ace/selection_test.js

@@ -368,6 +368,26 @@ module.exports = {
         selection.moveCursorLineStart();
 
         assert.position(selection.getCursor(), 1, 4);
+    },
+    
+    "test go line up when in the middle of the first line should go to document start": function() {
+        var session = new EditSession("juhu kinners");
+        var selection = session.getSelection();
+        
+        selection.moveCursorTo(0, 4);
+        selection.moveCursorUp();
+
+        assert.position(selection.getCursor(), 0, 0);
+    },
+    
+    "test go line down when in the middle of the last line should go to document end": function() {
+        var session = new EditSession("juhu kinners");
+        var selection = session.getSelection();
+        
+        selection.moveCursorTo(0, 4);
+        selection.moveCursorDown();
+
+        assert.position(selection.getCursor(), 0, 12);
     }
 };