[GN] Fixes a wrong condition on a size check

The wrong condition may lead errors on invalid argument list sizes.

R=dpranke@chromium.org

Bug: None
Change-Id: I438edbbd94e8f8aef1b27b9b74108e8fb8f49f2d
Reviewed-on: https://chromium-review.googlesource.com/704925
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#507695}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 710ba81f760f0c4fc1d662e4a9759b89fa6c6ee6