Remove inspectedPage() and inspectorClient() from InspectorController.

These public methods are never called, so remove them.

BUG=none.

Review URL: https://codereview.chromium.org/103303002

git-svn-id: svn://svn.chromium.org/blink/trunk@163169 bbb929c8-8fbe-4397-9dbb-9b2b20218538