COOP: Potential ambiguity in definition of sandboxing flag sets

[jugglinmike]

The patch introduced by gh-5334 mentions a property of a browsing context named "sandboxing flag set" four times. Three are references to the value (two in navigate and one in process a navigate fetch). The obtain a browsing context to use for a navigation response algorithm sets the property's value.

By my reading, that property has not been formally defined. A sandboxing flag set is a type, but (barring the new cases mentioned above) it only appears to be realized as a property using some qualifier:

Every top-level browsing context has a popup sandboxing flag set, [...]

Every iframe element has an iframe sandboxing flag set, [...]

Every Document has an active sandboxing flag set, [...]

Every resource that is obtained by the navigation algorithm has a forced sandboxing flag set, [...]

Since the "popup sandboxing flag set" already associates a "sandboxing flag set" with a browsing context, it first seemed like the new cases were just a typo. However, a browsing context also has a property named simply sandboxing flags, defined as follows:

After creation, the sandboxing flags for a browsing context browsing context are the result of determining the creation sandboxing flags given browsing context and browsing context's container.

It's unclear how the new "browsing context's sandboxing flag set" relates to "the sandboxing flags for a browsing context." They may be one in the same, though the definition of "sandboxing flags" suggests that the value isn't intended to be modified.

@camillelamy @annevk @domenic Does my confusion make sense? Have I missed something important?

[annevk]

Yeah, this was integrated incorrectly. It should talk about the slot on browsing contexts (i.e., sandboxing flags) and the place where we set we should use the popup sandboxing flag set similar to "the rules for choosing a browsing context".