Cleanup: Tiny nits in ContentSecurityPolicy::reportViolation.
https://bugs.webkit.org/show_bug.cgi?id=112784

Reviewed by Jochen Eisinger.

Just cleanup of three tiny nits I ran across in
ContentSecurityPolicy::reportViolation while doing other work.

- 'directiveText' and 'effectiveDirective' can't be empty; we pass in
  values at every callsite. We can safely remove the 'isEmpty()' checks.
  Moreover, even if they could possibly somehow be empty, we should
  still include those empty strings in the report, rather than
  dropping the values entirely.

- We don't need to hold 'document->referrer()' in a temp variable.

* page/ContentSecurityPolicy.cpp:
(WebCore::ContentSecurityPolicy::reportViolation):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146755 268f45cc-cd09-0410-ab3c-d52691b4dbfc