Auto merge of #20669 - simartin:issue_20623, r=jdm

Issue #20623: Check the input to WebGLRenderingContext's clear().

Validate the input to this function as per specifications.

---
- [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 #20623
- [X] There are tests for these changes

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tests/wpt/mozilla/meta/MANIFEST.json

@@ -39293,6 +39293,12 @@
      {}
     ]
    ],
+   "mozilla/webgl/clear.html": [
+    [
+     "/_mozilla/mozilla/webgl/clear.html",
+     {}
+    ]
+   ],
    "mozilla/webgl/context_creation_error.html": [
     [
      "/_mozilla/mozilla/webgl/context_creation_error.html",
@@ -70956,6 +70962,10 @@
    "c333c7b99156d63fcd3ad28014c7915a12cf8169",
    "testharness"
   ],
+  "mozilla/webgl/clear.html": [
+   "14cc534be5da96b0cc128d5c44f662b2fdfb294c",
+   "testharness"
+  ],
   "mozilla/webgl/clearcolor.html": [
    "942ee78ec987d17f63253ed97d6de958dbe8730d",
    "reftest"