Replace whitespace at beginning and end of file with hyphens, rather than silently discarding.
BUG=90217
TEST=all
Review URL: http://codereview.chromium.org/7647014
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@98148 0039d316-1c4b-4281-b951-d872f2087c98