gn: Fix integer subtraction.

Who knew that gn files even support an integer type!

Review-Url: https://codereview.chromium.org/2554083003
Cr-Original-Commit-Position: refs/heads/master@{#436677}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 4c53f32fe75ebc06a2f9184e07319acce8c9583d
2 files changed
tree: 2767adb8f4324858c9915386e40a275e42ef06ea
  1. tools/