The repository is accessible via the http protocol (aka dumb protocol) here: http://anongit.freedesktop.org/git/libreoffice/core.git.
You can download everything here with wget or another download manager, and you’ll have a clone of the repository. After that, you rename the directory from core.git to .git, and use the following command to tell git about the remote url:
$ git remote add remote http://anongit.freedesktop.org/git/libreoffice/core.git
$ git reset --hard HEAD