The program:

    foo;
    let foo = 5;

…now produces:

    ReferenceError: Cannot access 'foo' before initialization

…instead of:

    ReferenceError: foo is not defined

Bug: v8:6513, v8:6951
Change-Id: I6c372626734570d5abeb1d0196b814dde02b9e3e
Reviewed-on: https://chromium-review.googlesource.com/c/1441151Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Suraj Sharma <surshar@microsoft.com>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59307}