lib/Ext/Component.js
function(newHtmlCls, oldHtmlCls) {
        var innerHtmlElement = this.innerHtmlElement,
            innerElement = this.innerElement;

        if (this.getStyleHtmlContent() && oldHtmlCls) {
            if (innerHtmlElement) {
                innerHtmlElement.replaceCls(oldHtmlCls, newHtmlCls);
            } else {
                innerElement.replaceCls(oldHtmlCls, newHtmlCls);
            }
        }
    }
function(newHtmlCls, oldHtmlCls) {
        var innerHtmlElement = this.innerHtmlElement,
            innerElement = this.innerElement;

        if (this.getStyleHtmlContent() && oldHtmlCls) {
            if (innerHtmlElement) {
                innerHtmlElement.replaceCls(oldHtmlCls, newHtmlCls);
            } else {
                innerElement.replaceCls(oldHtmlCls, newHtmlCls);
            }
        }
    }
Updates the {@link #styleHtmlCls} configuration