Also allocate small typed arrays on heap when initialized from an array- like (issue 3996).

Implement %TypedArray%.prototype.{reduce,reduceRight} (issue 3578).

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.5.34@{#1}
Cr-Branched-From: 68beef53c36d8640b453da4169548cbbd61c91a9-refs/heads/master@{#28788}