Add some files for a Content Security Policy blog post

Add some files for a Content Security Policy blog post

* blog-files/content-security-policy/compass-base.css: Added.
(.compass):
* blog-files/content-security-policy/csp-style-hash.html: Added.
* blog-files/content-security-policy/icons.svg: Added; derived from file
Websites/webkit.org/wp-content/themes/webkit/images/icons.svg. I am explicitly
not referencing file Websites/webkit.org/wp-content/themes/webkit/images/icons.svg
so that csp-style-hash.html is not affected by changes to this file.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@204158 268f45cc-cd09-0410-ab3c-d52691b4dbfc