Uint64: BigInt polyfill

[tshemsedinov]

one of the following solutions

• took implementation from node.js
• find third-party polyfill
• implement polyfill

[tshemsedinov]

See #161 (comment)

[tshemsedinov]

@belochub this is important issue for all other modules. We can use Uint32Array(2) inside, no need to implement literal (and I see no way to do that without compiler) and math operations. All we need is a set of functions with bit/binary operations: and, or, not, xor, shift right and left.

[aqrln]

@tshemsedinov interestingly, that might be what we'd want to use for IDs even if BigInt is supported. As far as I can see from https://v8project.blogspot.com/2018/05/bigint.html, V8's implementation of BigInt is optimized for math operations, at the expense of extra conversions to and from two's complement representation when bitwise operations are involved. There's probably no overhead for non-negative numbers as no conversion in needed in this case, but benchmarking that to be sure won't harm anyway though.

[tshemsedinov]

@aqrln I think we will use unsigned Uint32Array(2) for emulation but if BigInt will give less performance we can consider BigUint64Array(1). @bugagashenkj and @lundibundi can prepare comparison.

[aqrln]

@tshemsedinov using BigUint64Array won't save us anything because its members, when indexed, are BigInts anyway.