fix(widget-base): change binding value only when needed
fix(widget-base): change binding value only when needed

fixes https://github.com/aurelia-ui-toolkits/aurelia-kendoui-bridge/issues/642

aurelia-ui-toolkits/aurelia-kendoui-plugin,aurelia-ui-toolkits/aurelia-kendoui-bridge,aurelia-ui-toolkits/aurelia-kendoui-bridge,aurelia-ui-toolkits/aurelia-kendoui-plugin