Move navigatorcontentutils directory to top of LayoutTests

Modules tests have been placed in top of LayoutTests. So, this cl moves navigatorcontentutils
to top of LayoutTests.

BUG=none

Review URL: https://codereview.chromium.org/335783003

git-svn-id: svn://svn.chromium.org/blink/trunk@176105 bbb929c8-8fbe-4397-9dbb-9b2b20218538