ES2026 is approved: getOrInsert, Iterator.concat, RegExp.escape and more

ES2026 was approved June 30: Map getOrInsert (upsert), Iterator.concat, JSON.parse source text access, Uint8Array base64/hex conversion, Math.sumPrecise, Error.isError, Array.fromAsync and RegExp.escape. Temporal and explicit resource management (using) are slated for ES2027.