WebNN defines two parameters bias and recurrent bias for Gru operator. Their shapes are [numDirections, 3 * hiddenSize], but in some backends like DirectML only defines one bias and the shape is [1, 1, numDirections, 6 * hiddenSize] ], 6*hiddenSize needs to be verified at this time.
We are currently validate it in backed side, but in order to avoid surprise build failures for web developers, we hope to validate and throw error in the verification layer. So should this limit be part of the spec and validated for all backends?
Link to chromium CL discussion.