prosemirror-view: Using the private eq method in the Decoration class

Issue details

Currently the eq method in the Decoration class is private, while it is very useful when you need to compare different Decorations, that have been returned by the DecorationSet.find method. So maybe it would be a good idea to make it public. I'm somewhat new to ProseMirror, so maybe I'm missing something. https://github.com/ProseMirror/prosemirror-view/blob/ea3d704a1796e611c2a411f16d2a6b6f58c14ce5/src/decoration.js#L98

ProseMirror version

1.3.0