That makes the declaration in sync with how dynamic references are resolved,
avoiding duplicate variable creation in the likely case that the variable is
also referenced within the eval.

Bug: v8:5112, v8:5135, v8:8693
Change-Id: I0c55495f573fe8b5076b1627c139ff72d1adda74
Also-by: leszeks@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/1408890
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58850}