RFR: 8285493: ECC calculation error

[Rajan Halade]

On Tue, 26 Apr 2022 21:02:49 GMT, Weijun Wang <weijun at openjdk.org> wrote:

> Only numbers from the same modular fields can be involved in arithmetic calculations. Add `assert` to guarantee this.
> 
> Also, found one broken case and rewrote it.

Please update bug with applicable noreg label.

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PR: https://git.openjdk.java.net/jdk/pull/8409