Updating trunk VERSION from 4454.0 to 4455.0

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

Change-Id: I82f3648b2a3d45df0876e1f2d889905f35763a94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2777091
Bot-Commit: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#864985}

chrome/VERSION

@@ -1,4 +1,4 @@
 MAJOR=91
 MINOR=0
-BUILD=4454
+BUILD=4455
 PATCH=0