Do not include "wtf/Platform.h" directly. 

Follow the project coding style and include "config.h" instead of including "wtf/Platform.h". config.h includes "wtf/Platform.h".

Review URL: https://chromiumcodereview.appspot.com/23187004

git-svn-id: svn://svn.chromium.org/blink/trunk@156542 bbb929c8-8fbe-4397-9dbb-9b2b20218538