Rebaseline plugin tests for changed NPP_Destroy message.

https://codereview.chromium.org/659023002/ fixes the test plugin to
flush stdout after logging messages to it to ensure that the output
appears. Unfortunately, Windows still doesn't want to display the
test logging.

BUG=363099,371084

Review URL: https://codereview.chromium.org/658003004

git-svn-id: svn://svn.chromium.org/blink/trunk@183997 bbb929c8-8fbe-4397-9dbb-9b2b20218538