- Performs hash / length check before calling IsMatch
- Casts to string before calling IsMatch
- Removes special two-char internalization key
  (will look into removing StringTableNoAllocateKey next, and possible fold
  StringTableInsertionKey into InternalizedStringKey).

Change-Id: Ida76761eb2c3dc350c829ac2bfe12d52aef5f96d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1598753Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61280}