Origin-keyed agent clusters tests

These are tests for the origin-keyed agent clusters feature.

Test filenames

The tests in 2-iframes follow the file naming pattern

parent-[yes|no]-child1-[yes|no]-[designator]-child2-[yes|no]-[designator]

Here:

• yes or no refers to whether the Origin-Agent-Cluster header is set or

unset.

• designator explains how the child differs from the parent: e.g. by being a

subdomain, or having a different port, or both. There's also same if it's same-origin.

Other directories have variations on this, e.g. 1-iframe/ does the same thing but for a single child instead of child1 and child2, and navigation/ uses 1 and 2 to represent the two different locations the single iframe will be navigated to.

Coverage

Header parsing is covered by a few tests in the 1-iframe/ subdirectory, and not duplicated to all other scenarios.