code cleanup: remove unused helpers

src/helpers.js

@@ -115,24 +115,6 @@ Handsontable.helper.isNumeric = function (n) {
            t == 'object' ? !!n && typeof n.valueOf() == "number" && !(n instanceof Date) : false;
 };
 
-/**
- * Checks if child is a descendant of given parent node
- * http://stackoverflow.com/questions/2234979/how-to-check-in-javascript-if-one-element-is-a-child-of-another
- * @param parent
- * @param child
- * @returns {boolean}
- */
-Handsontable.helper.isDescendant = function (parent, child) {
-  var node = child.parentNode;
-  while (node != null) {
-    if (node == parent) {
-      return true;
-    }
-    node = node.parentNode;
-  }
-  return false;
-};
-
 /**
  * Generates a random hex string. Used as namespace for Handsontable instance events.
  * @return {String} - 16 character random string: "92b1bfc74ec4"
@@ -471,10 +453,6 @@ Handsontable.helper.cellMethodLookupFactory = function (methodName, allowUndefin
 
 };
 
-Handsontable.helper.toString = function (obj) {
-  return '' + obj;
-};
-
 Handsontable.helper.isMobileBrowser = function (userAgent) {
   if(!userAgent) {
     userAgent = navigator.userAgent;