Avoid assert with convolutions with no strides or dilates. Issue #2829

[pstarkcdpr]

See issue #2829. A convolution without strides or dilates was causing spurious asserts.

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[GleasonK]

Also can you sign the Google CLA when you get a chance, cant run the CI until thats completed

[pstarkcdpr]

@GleasonK I'm checking if I'm allowed to agree to the CLA since I'm using a corporate account. I'll update when I know the answer. Alternately, this is such a simple change that if someone else wants to just do it and push it in, I'm fine with that and can cancel this PR if that gets done.

[pstarkcdpr]

@GleasonK I updated the PR based on your suggestion. It turns out that the original implementation had a real problem anyways, plus this is simpler.