Use OwnPtr for SCRIPT_FONTPROPERTIES.

Make the ownership of SCRIPT_FONTPROPERTIES in FontPlatformDataChromiumWin explicit using an OwnPtr.

BUG=

Review URL: https://chromiumcodereview.appspot.com/19520009

git-svn-id: svn://svn.chromium.org/blink/trunk@154665 bbb929c8-8fbe-4397-9dbb-9b2b20218538