[WebSocket] Fix and enable inspector-related layout tests.

Note: These tests are not duplicated and always run on the new implementation.

BUG=339373
R=ricea@chromium.org

Review URL: https://codereview.chromium.org/144383009

git-svn-id: svn://svn.chromium.org/blink/trunk@166506 bbb929c8-8fbe-4397-9dbb-9b2b20218538