Fix the bug that we call setKeywordValue w/o convert the key to legacy key.

Bug: v8:7481
Change-Id: I5a743e41d02b64385c5050fc1d83279741e24659
Reviewed-on: https://chromium-review.googlesource.com/c/1339243
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57886}