Remove printf causing 8500 tests to have stderr output

This was a regression from:
https://src.chromium.org/viewvc/blink?view=rev&revision=156495

BUG=226293
TBR=haraken

Review URL: https://codereview.chromium.org/23241022

git-svn-id: svn://svn.chromium.org/blink/trunk@156579 bbb929c8-8fbe-4397-9dbb-9b2b20218538