We changed behaviour from using indexes to using hashes back in 14b5fbc3979e9064d22ad7225f256a967658394f in 2016, but left the class name unchanged.
Also change method names: .index -> .hash, and .indexes -> .hashAll
Also change various property names throughout the system, the most important being .originalDomElementsIndex .originalDomElementsHash in hash objects. This will change the computed hash strings in some tests.