FB22800942 - When Safari app extension is enabled, the web inspector loads the extension content script into a new tab

[lapcat]

Please describe the issue and what steps we can take to reproduce it:

1. Build and enable the attached Safari app extension InspectorBug
2. Allow on all websites and in private browsing
3. Disable the extension in Safari Settings
4. Open a new private window
5. Open the web inspector to the Sources tab
6. Enable the extension in Safari Settings

Expected results: The extension content script is not loaded into the empty tab

Actual results: The extension content script is loaded into the empty tab. See the attached screenshots. The Console tab shows that the content script JavaScript runs, but the "safari" variable is not defined.

See also FB22800921 Web inspector loads Safari app extension style sheet into new tabs

InspectorBug.zip