lib/Ext/field/Input.js
function(newCls, oldCls) {
        this.input.addCls(Ext.baseCSSPrefix + 'input-el');
        this.input.replaceCls(oldCls, newCls);
    }
function(newCls, oldCls) {
        this.input.addCls(Ext.baseCSSPrefix + 'input-el');
        this.input.replaceCls(oldCls, newCls);
    }
Updates the {@link #cls} configuration.