grit: Do not print warnings about bad placeholders.

Avoid adding noise to the build. Instead, print the warning message
right before throwing the exception to give developers better
diagnostics.

BUG=915681

Change-Id: I9c3484fbbcdcb523b58a8ab98f77225c2744f47a
Reviewed-on: https://chromium-review.googlesource.com/c/1388181
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#618443}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c3b90678be24d15e796c33afc24d96f38e71e708
1 file changed