- Directly use VisitFunctionLiteral where possible
- Take shortcut for StringLiterals in BuildLoadPropertyKey

Change-Id: Ib5c3de3d2bdd354acbfeb607415854ba90622e89
Reviewed-on: https://chromium-review.googlesource.com/c/1382750Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58595}