[ES6 modules] Add WPT for loading cyclic module graph w/ slow imports
This CL adds a layout test demonstrating the currently broken cycle handling,
which currently fails on ToT.
If a cyclic module graph node contained other edges that are not part
of the cycle, the graph does not load reliably. (To be more specific,
the graph does not load unless the other edges complete loading before
we instantiate the cycle nodes).
We expect to have the root cause fixed in the spec change PR:
https://github.com/whatwg/html/pull/2674
Bug: 594639
Change-Id: I3cf8a640a73083ad612c96fc4bbd0f01e00f6e46
Reviewed-on: https://chromium-review.googlesource.com/535413
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#479551}4 files changed
