Support space-separated multi-prefixes in menus

Change-Id: I308ce7bb3600c0b0430f4580b6cb4948e63b4cd2
diff --git a/dev/js/src/menu/prefix.js b/dev/js/src/menu/prefix.js
index abcf66c..90924c9 100644
--- a/dev/js/src/menu/prefix.js
+++ b/dev/js/src/menu/prefix.js
@@ -107,7 +107,7 @@
     // Prefix is long enough for backspace
     if (this._string.length > 1) {
       this._string = this._string.substring(
-	0, this._string.length - 1
+	      0, this._string.length - 1
       );
     }
     else {