Creates the Element and DOM for the clear button
function() {
            var animateWithClass = this.animateClearButton && this.animateWithCss3;
            this.clearButtonEl = this.textField.bodyEl.createChild({
                tag: 'div',
                cls: this.clearButtonCls
            });
            if(this.animateClearButton) {
                this.animateWithCss3 = this.supportsCssTransition(this.clearButtonEl);
            }
            if(this.animateWithCss3) {
                this.clearButtonEl.addCls(this.clearButtonCls + '-off');
            }
            else {
                this.clearButtonEl.setStyle('visibility', 'hidden');
            }
        }