Custom Quick Bar item is showing up on all pages regardless of documentUrlPattern

[twschiller]

Steps to Reproduce

• Create a Quick Bar item with a document and URL patterns for a site, e.g., https://news.ycombinator.com/*
• Save
• Open another site, e.g., https://www.cnn.com/
• Press the shortcut to open the quickbar

Expected behavior

• The quick bar item is not shown because the URL doesn't match

Actual Behavior

• The quick bar item is shown and can be run

Considerations

• The quickBar registry is a singleton per contentScript, so it shouldn't be a cross tab issue
• I think I might have just forgotten to implement any documentUrlPattern logic for enforcing documentUrlPattern
• It should probably be enforced in the registerExtension method

[fregante]

I'm not sure of where this should be done. isAvailable is called and it returns false as expected, but then the item is still in this.extensions, an array of ResolvedExtension that does not have isAvailable nor documentUrlPattern, so I don't see a way to enforce that in registerExtensions