Auto merge of #20699 - simartin:issue_20593, r=nox

Issue #20593: Implement proper checks in WebGLRenderingContext's getFramebufferAttachmentParameter().

Add missing input checks.

---
- [X] `./mach build -d` does not report any errors
- [X] `./mach build-geckolib` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #20593
- [X] There are tests for these changes

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tests/wpt/mozilla/meta/MANIFEST.json

@@ -39282,6 +39282,12 @@
      {}
     ]
    ],
+   "mozilla/webgl/getFramebufferAttachmentParameter.html": [
+    [
+     "/_mozilla/mozilla/webgl/getFramebufferAttachmentParameter.html",
+     {}
+    ]
+   ],
    "mozilla/webgl/get_supported_extensions.html": [
     [
      "/_mozilla/mozilla/webgl/get_supported_extensions.html",
@@ -70951,6 +70957,10 @@
    "a163189d8674be83c9e8c9055da31a1c5ed46be5",
    "support"
   ],
+  "mozilla/webgl/getFramebufferAttachmentParameter.html": [
+   "71a8c1829f703ff43a30d1b3fb9b99e59d3db973",
+   "testharness"
+  ],
   "mozilla/webgl/get_supported_extensions.html": [
    "719c7c4cb91f3c1b2bbc4cbe35285fc63ce6263f",
    "testharness"