All the encoders that Chrome/Safari/Firefox support out of the box. (#74)

* All the encoders that Chrome/Safari/Firefox support out of the box.

* Typo

src/codecs/generic/util.ts

@@ -0,0 +1,13 @@
+import { canvasEncode } from '../../lib/util';
+
+export async function canvasEncodeTest(mimeType: string) {
+  try {
+    const blob = await canvasEncode(new ImageData(1, 1), mimeType);
+    // According to the spec, the blob should be null if the format isn't supported…
+    if (!blob) return false;
+    // …but Safari & Firefox fall back to PNG, so we need to check the mime type.
+    return blob.type === mimeType;
+  } catch (err) {
+    return false;
+  }
+}