#4103: make getBase64() work in dev mode (and hopefully on server too)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@32508 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#4103: make synchronous getBase64() work in dev mode (and hopefully on server too)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@32509 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e