wasm: streaming APIs accept non-Uint8Array response body chunks

Version

latest main branch

Platform

7.1.3-arch1-3

Subsystem

wasm

What steps will reproduce the bug?

const bytes = new Uint8Array([
  0x00, 0x61, 0x73, 0x6d, // \0asm
  0x01, 0x00, 0x00, 0x00, // version 1
]);

const stream = new ReadableStream({
  start(controller) {
    controller.enqueue(bytes.buffer); // ArrayBuffer, not Uint8Array
    controller.close();
  },
});

const response = new Response(stream, {
  headers: {
    'Content-Type': 'application/wasm',
  },
});

WebAssembly.compileStreaming(response).then(
  () => console.log('unexpectedly compiled'),
  (error) => console.error('rejected:', error),
);

How often does it reproduce? Is there a required condition?

Every

What is the expected behavior? Why is that the expected behavior?

Fetch body consumption requires every chunk read from the response body to be a Uint8Array. Other values, including ArrayBuffer, DataView, and other typed arrays, should cause the operation to reject with a TypeError.

What do you see instead?

WebAssembly.compileStreaming() and WebAssembly.instantiateStreaming() accept response bodies whose
ReadableStream produces non-Uint8Array chunks.The WebAssembly module is compiled successfully, even though the response body produces an ArrayBuffer chunk.

Additional information

Refs: https://github.com/web-platform-tests/wpt/blob/master/wasm/webapi/wasm_stream_compile_test.any.js#L80-L93
Refs: https://github.com/web-platform-tests/wpt/blob/master/wasm/webapi/wasm_stream_instantiate_test.any.js#L79-L92

Comienza con los puntos de entrada WebAssembly.compileStreaming() y WebAssembly.instantiateStreaming() y las pruebas WPT referenciadas, wasm/webapi/wasm_stream_compile_test.any.js y wasm/webapi/wasm_stream_instantiate_test.any.js. Reproduce el caso de fragmentos ArrayBuffer del informe y, después, verifica que los fragmentos de respuesta que no sean Uint8Array se rechacen con un TypeError, mientras que los fragmentos válidos sigan funcionando.