function mappedNavKey(keyChar, ctrlKey) {
    keyChar = this.navKeyMap[keyChar];
    return keyChar && this.navKey(keyChar);
}
Returns only values of `keyChar` that, when run through {@link module:defaults.navKeyMap|navKeyMap}, pass the {@link module:defaults.navKey|navKey} logic test.

@param {string} keyChar - A value from Canvas's `charMap`, to be remapped through {@link module:defaults.navKeyMap|navKeyMap}.
@param {boolean} [ctrlKey=false] - The CTRL key was down.
@returns {undefined|string} `undefined` means not a nav key; otherwise returns `keyChar`.
@memberOf module:defaults