Modify checkdeps.py so that it only looks for files named DEPS, not directories.
Modify checkdeps.py so that it only looks for files named DEPS, not
directories.

BUG=53498
TEST=manually tried checkdeps.py before and after, verified that it now ignores a directory named DEPS

Review URL: http://codereview.chromium.org/3155049

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@57582 0039d316-1c4b-4281-b951-d872f2087c98

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