Implement JavaScript 2026 (ES2026) features

[FunctionPoint]

New JS features:

• Math.sumPrecise()
• Error.isError()
• Map.getOrInsert()
• Array.fromAsync()
• Uint8Array Base64 and Hex conversion
• JSON.rawJSON()
• JSON reviver

[FunctionPoint]

On further testing, Node.JS currently (v26.8.1) does not yet support:

• Math.sumPrecise()
• JSON.rawJSON()
• JSON.parse() reviver context parameter

So let's wait until it does, to SmallJS for browser and Node in sync.