[INTERNAL] sap.m: Use BaseObject#isA instead of local lazyInstanceof
[INTERNAL] sap.m: Use BaseObject#isA instead of local lazyInstanceof

Change-Id: Icdd8f722a39384f68ad5ca97f74f44101067306c

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