Fix memory leak in Fetch with large stream responses

[2400030206]

What is the issue with the Fetch Standard?

Memory leak in Fetch with large stream responses

Description

When processing large responses as ReadableStreams, some implementations fail to properly garbage collect stream resources, leading to memory leaks.

Steps to Reproduce

1. Fetch a large resource (100MB+) as a stream
2. Cancel the stream before complete consumption
3. Repeat multiple times
4. Observe memory usage growth

Expected Behavior

Memory should be properly reclaimed when streams are cancelled or consumed.

Actual Behavior

Memory usage grows with each stream cancellation and is not reclaimed.

Browser Affected

• Chrome: ✅ No leak detected
• Firefox: ❌ Memory grows with each cancelled stream
• Safari: ⚠️ Minor memory accumulation

Specification Reference

https://fetch.spec.whatwg.org/#body-mixin

Severity

Medium - Affects long-running web applications with frequent large data transfers.

[annevk]

These seem like issues you should report against the relevant implementations.