I can suggest you a workaround till the bug fix is implemented in sapui5. You can extend the TextArea control to include \n in IE11.
jQuery.sap.require("sap.m.TextArea");
sap.m.TextArea.extend("MyCustomTextArea",{ renderer : { writeInnerContent : function(oRm,oControl){ var sValue = oControl.getValue(); sValue = jQuery.sap.encodeHTML(sValue); sValue = sValue.replace(/
 | 
 | 
/g, " "); oRm.write(sValue); } }
});
var oInput = new MyCustomTextArea("input1");- Sakthivel