src/utils.js: Fix variable redefinition in |escape|

Fixes the following JSHint errors:

  ./src/utils.js: line 76, col 20, 'escapeChar' is already defined.
  ./src/utils.js: line 77, col 16, 'length' is already defined.
  ./src/utils.js: line 80, col 17, 'escapeChar' used out of scope.
  ./src/utils.js: line 80, col 80, 'length' used out of scope.

src/utils.js

@@ -68,13 +68,15 @@ function padLeft(input, padding, length) {
  */
 function escape(ch) {
   var charCode = ch.charCodeAt(0);
+  var escapeChar;
+  var length;
 
   if (charCode <= 0xFF) {
-    var escapeChar = 'x';
-    var length = 2;
+    escapeChar = 'x';
+    length = 2;
   } else {
-    var escapeChar = 'u';
-    var length = 4;
+    escapeChar = 'u';
+    length = 4;
   }
 
   return '\\' + escapeChar + padLeft(charCode.toString(16).toUpperCase(), '0', length);