Add sanitizeDOMValue to settings.html

Fixes #4753

lib/utils/settings.html

@@ -61,5 +61,37 @@
   Polymer.setRootPath = function(path) {
     Polymer.rootPath = path;
   }
+
+  /**
+   * A global callback used to sanitize any value before inserting it into the DOM. The callback signature is:
+   * 
+   *     Polymer = {
+   *       sanitizeDOMValue: function(value, name, type, node) { ... }
+   *     }
+   * 
+   * Where:
+   * 
+   * `value` is the value to sanitize.
+   * `name` is the name of an attribute or property (for example, href).
+   * `type` indicates where the value is being inserted: one of property, attribute, or text.
+   * `node` is the node where the value is being inserted.
+   * 
+   * @type {(function(*,string,string,Node):*)|undefined}
+   * @memberof Polymer
+   */
+  let sanitizeDOMValue = Polymer.sanitizeDOMValue;
+
+  // This is needed for tooling
+  Polymer.sanitizeDOMValue = sanitizeDOMValue;
+
+  /**
+   * Sets the global sanitizeDOMValue available via `Polymer.sanitizeDOMValue`.
+   *
+   * @memberof Polymer
+   * @param {(function(*,string,string,Node):*)|undefined} sanitizeDOMValue the global sanitizeDOMValue callback
+   */
+  Polymer.setSanitizeDOMValue = function(sanitizeDOMValue) {
+    Polymer.sanitizeDOMValue = sanitizeDOMValue;
+  }
 })();
-</script>
+</script>