Bug 1626570 - Improve handling of copying arrays in image/. r=tnikkel

Differential Revision: https://phabricator.services.mozilla.com/D73676

image/ImageMetadata.h

@@ -95,7 +95,7 @@ class ImageMetadata {
   Maybe<Orientation> mOrientation;
 
   // Sizes the image can natively decode to.
-  nsTArray<nsIntSize> mNativeSizes;
+  CopyableTArray<nsIntSize> mNativeSizes;
 
   bool mHasAnimation : 1;
 };