Updating trunk VERSION from 4259.0 to 4260.0

# This is an automated release commit.
# Do not revert without consulting chrome-pmo@google.com.
NOAUTOREVERT=true
TBR=benmason@chromium.org

Change-Id: I38e33512c6666edf883ef8f829cb3b0abe5ce088
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2399843


Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#805192}