WebGL conformance failure: angle-instanced-arrays-out-of-bounds.html expects INVALID_OPERATION but Chromium returns NO_ERROR

We are observing failures in the following WebGL conformance test when running on Chromium-based browsers:

Test: https://registry.khronos.org/webgl/sdk/tests/conformance/extensions/angle-instanced-arrays-out-of-bounds.html
Specifically, some cases in the section: "Test out-of-range instanced attributes" are failing.
FAIL getError expected: INVALID_OPERATION. Was NO_ERROR : after evaluating: ext.drawArraysInstancedANGLE(gl.TRIANGLES, 0, 9, 1)

**Attempted Fix**
A change was proposed in ANGLE to explicitly generate GL_INVALID_OPERATION via additional CPU-side validation:
https://chromium-review.googlesource.com/c/angle/angle/+/7588515

**Feedback from ANGLE Code Owners**
The required CPU-side validation to detect these out-of-range instanced attribute accesses is extremely expensive.
When backends ensure robust buffer access and memory safety, returning GL_INVALID_OPERATION may not provide meaningful additional value. Therefore, it was suggested that the WebGL specification might be reconsidered to avoid requiring this error in such cases.

Start with the linked angle-instanced-arrays-out-of-bounds.html conformance test, especially the “Test out-of-range instanced attributes” section and the reported drawArraysInstancedANGLE case. Then read the linked ANGLE change and determine whether the WebGL specification or the test expectation should change; done means the discrepancy has a documented resolution and the affected conformance result is consistent.

Written by the indexing model from the issue text.