Add validation tests for Multi-Draw Indirect

[beaufortfrancois]

This PR adds validation tests for the experimental Multi-Draw Indirect feature that can be tested in Chrome Canary behind the "Unsafe WebGPU support" flag at chrome://flag#enable-unsafe-webgpu

Issue: #3961

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Requirements for PR author:

• All missing test coverage is tracked with "TODO" or .unimplemented().
• New helpers are /** documented */ and new helper files are found in helper_index.txt.
• Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)
• Test have be tested with compatibility mode validation enabled and behave as expected. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located in the test tree.
• Test descriptions allow a reader to "read only the test plans and evaluate coverage completeness", and accurately reflect the test code.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Helpers and types promote readability and maintainability.

When landing this PR, be sure to make any necessary issue status updates.

[Sirtsu55]

Apart from the stylistic nitpick, LGTM.

[Sirtsu55]

nit: Could we combine these test cases with the ones below as a variable? If I didn't miss anything these cases seem similar with small differences, and combining them would be cleaner/more readable.

[kainino0x]

+1, if possible store this array as a variable and use it twice. A pattern we use elsewhere to make this work is instead of having bufferSize as a parameter, have something like bufferExtraSize which has negative, zero, and positive cases (4 + (-1) = 3 for indirect, 5 + (-1) = 4 for indexed indirect)

And if there are any cases that are specific to one or the other then you can do:

const kIndirectOffsetOOBCommonCases = [
  /* ... */
] as const;

/* ... */
  .combineWithParams([
    ...kIndirectOffsetOOBCommonCases,
    /* any additional cases which are not common between the two */
  ])

[beaufortfrancois]

I've hopefully addressed your feedback in latest patch. Please have a look!

[Sirtsu55]

FYI @beaufortfrancois , I'm working on #3970 to add more rendering tests. Should we incrementally add rendering tests to this branch or should submit all of the rendering tests at once?

[beaufortfrancois]

FYI @beaufortfrancois , I'm working on #3962 to add more rendering tests. Should we incrementally add rendering tests to this branch or should submit all of the rendering tests at once?

I'll let @kainino0x weigh in as I don't have strong preferences.

[kainino0x]

+1, if possible store this array as a variable and use it twice. A pattern we use elsewhere to make this work is instead of having bufferSize as a parameter, have something like bufferExtraSize which has negative, zero, and positive cases (4 + (-1) = 3 for indirect, 5 + (-1) = 4 for indexed indirect)

And if there are any cases that are specific to one or the other then you can do:

const kIndirectOffsetOOBCommonCases = [
  /* ... */
] as const;

/* ... */
  .combineWithParams([
    ...kIndirectOffsetOOBCommonCases,
    /* any additional cases which are not common between the two */
  ])

[kainino0x]

FYI @beaufortfrancois , I'm working on #3962 to add more rendering tests. Should we incrementally add rendering tests to this branch or should submit all of the rendering tests at once?

I'll let @kainino0x weigh in as I don't have strong preferences.

IMO land tests as soon as they're landable. It's easy enough to modify tests after they land.