Fix bug in Document.. If there are no lines after trimming off the spaces/tabs from the end return directly.

lib/ace/document.js

@@ -879,6 +879,12 @@ var Document = function(text, mode) {
         }
         tabLine.splice(toRemove + 1);
 
+        // Shortcut: If there are no more tabLines, then there is nothing to
+        // split up.
+        if (tabLine.length == 0) {
+            return [];
+        }
+
         // Remove spaces from the last tabLine to prevent splits only for
         // whitespaces as well.
         // E.g: "foo \tbar    " -> "foo \tbar"