merge_pr_50919

WebNN: Don't run per-op WPTs in non-window contexts

The WebNN tests are written as ".any.js" tests which can run in both
Window and Worker contexts. This is great! But we running every test
on every combination of (CPU, GPU, NPU) x (Window, Worker) consumes
significant cycles for little benefit. While tests and various backend
and platform implementations are in flux, it also adds significant
burden to gardeners.

Scope down to running just the Window variations for op-specific
tests. Tests for things like inputs, constants, tensors, and object
lifecycles are still run in all contexts, and identity() is retained
as a "canary".

Change-Id: I1f1c749ea4d002a578d6d2ca89579cec6b0090e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6299831
Reviewed-by: Weizhong Xia weizhong@google.com
Commit-Queue: Weizhong Xia weizhong@google.com
Auto-Submit: Joshua Bell jsbell@chromium.org
Reviewed-by: Reilly Grant reillyg@chromium.org
Cr-Commit-Position: refs/heads/main@{#1424187}