NPE fix on window resizing

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33978 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3392 Interval update for web

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33980 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e