Fix build after WebCore namespace rename

This CL fixes some build breaks from the future world in which the WebCore
namespace has been renamed to blink.

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/396873002

git-svn-id: svn://svn.chromium.org/blink/trunk@178242 bbb929c8-8fbe-4397-9dbb-9b2b20218538