Add variant support to // META

[wpt-issue-mover]

Originally posted as w3c/wpt-tools#185 by @annevk on 15 Mar 2017, 10:07 UTC:

This blocks landing #5148 / fixing #2557 properly.

[wpt-issue-mover]

Originally posted as w3c/wpt-tools#185 (comment) by @jdm on 21 Mar 2017, 16:58 UTC:

Somehow we need to interact with https://github.com/w3c/wpt-tools/blob/3decb956499edd97c058bd80697abb3aff8479bb/manifest/sourcefile.py#L363-L381.

[wpt-issue-mover]

Originally posted as w3c/wpt-tools#185 (comment) by @annevk on 21 Mar 2017, 17:14 UTC:

Since it ends up writing out a container HTML for the worker resource as well, I suppose we can plug in the meta elements there.

@jgraham was also talking about combining the HTML wrapper .any.js tests so you only have a single file in which case this would just work (though not for .worker.js I suppose).

[wpt-issue-mover]

Originally posted as w3c/wpt-tools#185 (comment) by @jgraham on 21 Mar 2017, 17:42 UTC:

Writing the meta stuff in the wrapper document doesn't work because that doesn't exist until runtime and this needs to go in the manifest so it knows which tests exist. You need to make the changes in manifest/sourcefile.py so that variant is a supported meta value and each variant is added as a different test in the manifest.