Avoid one recomputation in case of redefinition

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27632 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
CAS context menu started on web (#3531)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27633 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e