This property is not used anymore.

Bug: 1002153
Change-Id: I19a503a73ec00e9121b2d9a2c130824a974d307a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1877747
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>