Auto merge of #23919 - tdelacour:ISSUE-21803, r=jdm

ISSUE-21803: Implement ConstantSourceNode audionode

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More or less followed the steps outlined in `components/script/dom/mod.rs` (and also used the [previous PR](https://github.com/servo/servo/pull/23152) on this issue as reference). Updated `wpt` tests as well.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #21803 (GitHub issue number if applicable)

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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tests/wpt/mozilla/meta/MANIFEST.json

@@ -18919,7 +18919,7 @@
    "testharness"
   ],
   "mozilla/interfaces.html": [
-   "cb0317a6de33cc5283f3754bece13a3b04940423",
+   "f30dd3de4087a45476745c4a41dd6a5f7e9365e3",
    "testharness"
   ],
   "mozilla/interfaces.js": [