Make render_pdfs not crash webpages_playback script

The render_pdfs nowadays seems to input the skps from
the dir passed as '-r' parameter.

The app will not output anything, but it will not crash the
webpages_playback script either. Affects only runs that have
--skia_tools=<dir> argument.

Review URL: https://codereview.chromium.org/776873004
1 file changed