Removed unused firstNew parameter for appendAuthorStyleSheets.

lazyAppendAuthorStyleSheets seems to handle cumulative addition of
stylesheets now.

Review URL: https://codereview.chromium.org/262643002

git-svn-id: svn://svn.chromium.org/blink/trunk@172980 bbb929c8-8fbe-4397-9dbb-9b2b20218538