Switch the parameter from a pointer to a reference. The only 2 callers in SfxChildWindow::CreateChildWindow always pass a non-null param. Using a reference makes clear that the param is always non-null and makes clear that those implementations previously unconditionally dereferencing the pointer were unproblematic. Change-Id: Ia2b893aac6c94c3b0e1024cc5500da2463bf9996 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/208312 Reviewed-by: Michael Weghorn <m.weghorn@posteo.de> Tested-by: Jenkins