Get about 1/3rd of the tests running with MEMORY64=1, but the code noise level added...

Get about 1/3rd of the tests running with MEMORY64=1, but the code noise level added by the BigInt/Number discrepancy is making this very unattractive. There are apparently irreconcilable differences between MEMORY64=1 and 2, in that they have different argument type expectations for methods such as WebAssembly.Table.get(), where MEMORY64=1 requires a BigInt a MEMORY64=2 requires a Number. We have no way to make that distinction from the JS code, and don't know what other APIs are affected by that quirk.

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