Remove PageGroup arguments from Page::(all)visitedStateChanged

The PageGroup concept is artificial in Chrome:
  https://code.google.com/p/chromium/issues/detail?id=288249

This patch is preparation work for removing PageGroups.

Pages are divided into normal pages (PageGroup::shared()) and
private page groups consisting of single pages (SVG, inspector
overlay).

The methods were only called for the normal page group
(PageGroup::shared()) so we now do this inside the methods.

Review URL: https://codereview.chromium.org/148153006

git-svn-id: svn://svn.chromium.org/blink/trunk@165943 bbb929c8-8fbe-4397-9dbb-9b2b20218538