LibWeb: Make HTMLVideoElement part of CanvasImageSource union

Author: https://github.com/Totto16 🔰
Commit: abe1172d70
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1635

Tests/LibWeb/Text/input/canvas/pattern-from-video.html

@@ -0,0 +1,10 @@
+<script src="../include.js"></script>
+<script>
+    test(() => {
+        let canvas = document.createElement("canvas");
+        let ctx = canvas.getContext("2d");
+        let v = document.createElement("video");
+        println(ctx.createPattern(v, 'repeat'));
+        println("PASS (didn't throw!)");
+    });
+</script>