It's automatically detected in VariableDeclarationParsingScope::Declare.

Change-Id: I2cf406ebd2dcd66eefb3d709289e0a8d162d0251
Reviewed-on: https://chromium-review.googlesource.com/c/1463783Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59512}