[INTERNAL] layout.Splitter JSDoc: built-in types are lower-case
[INTERNAL] layout.Splitter JSDoc: built-in types are lower-case

Fix for dtslint errors

Change-Id: Ied80563027cd9c95290249e0e6f7a8490175a090

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