Steps for processing shortcut member are very vague #831

I'm reviewing https://chromium-review.googlesource.com/c/chromium/src/+/1941051, which implements parsing of the shortcuts member in Chromium. I'm finding the spec very deficient in describing the parsing. For instance:

• should shortcut item URLs be restricted to be within the scope of the manifest? The spec seems to imply this ("The shortcuts member is an array of ShortcutItems that provide access to key tasks within a web application."), but the processing algorithm doesn't prescribe any checks here. It seems weird to allow arbitrary URLs.
• when should developer warnings be issued when parsing the member?
• when should items be ignored (presumably when name or url are empty?)

We should clarify these questions in the spec. @aarongustafson @mgiuca @rayankans