Remove executable bit from readability.js, to fix checkdeps.

BUG=none
TBR=scottmg@chromium.org

Review URL: https://codereview.chromium.org/68123006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234403 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234403