Added WebDOMFileSystem wrapper to expose DOMFileSystem to Chromium.

Includes facilities to convert a V8 DOMFileSystem value into a
WebDOMFileSystem, and to read its properties.

BUG=295348

Review URL: https://chromiumcodereview.appspot.com/23440057

git-svn-id: svn://svn.chromium.org/blink/trunk@158361 bbb929c8-8fbe-4397-9dbb-9b2b20218538
CSP 1.1: Implement nonce support for 'style' elements.

We've had this in the spec for some time now, we should support the 'nonce'
attribute on 'style' elements in the same way we do for 'script' elements.

Review URL: https://chromiumcodereview.appspot.com/23522066

git-svn-id: svn://svn.chromium.org/blink/trunk@158362 bbb929c8-8fbe-4397-9dbb-9b2b20218538