PIMCORE-1899 - Document edit: iframe.document.(head|body) wrong css height set in document/edit/startup.js -> changed back to setInterval()

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@2626 1f8fe7d8-47f0-464c-8d0a-336f4953ab05