[FIX] sap.m.ComboBox: Fix failing tests on IE
[FIX] sap.m.ComboBox: Fix failing tests on IE

BCP: 1880499743

Change-Id: I19c2f512a60c9fff313da49827e8a61ed3992967

SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5