Removed unused Document forward declaration+include from SecurityOrigin

We use (Web)SecurityOrigin all over the place and need to be able to understand
its dependencies. These appear unused.

BUG=237267

Review URL: https://chromiumcodereview.appspot.com/14801011

git-svn-id: svn://svn.chromium.org/blink/trunk@149980 bbb929c8-8fbe-4397-9dbb-9b2b20218538
2 files changed