Initial import of JetStream v2.0

Upstream source: https://github.com/WebKit/WebKit/tree/main/Websites/browserbench.org/JetStream2.0

- Add webkit LICENSE file
- Add README.md

Bug: 340983089
Change-Id: I8c250d5facaf36867358a2828e4aa23c3047df22
Reviewed-on: https://chromium-review.googlesource.com/c/external/github.com/WebKit/JetStream/+/5547900
Reviewed-by: John Chen <johnchen@chromium.org>
479 files changed