Add title attribute to provide stack name on mouseover.
Add title attribute to provide stack name on mouseover.

This makes it easier to identify which metric a stack belongs to.

Bug: chromium:866423
Change-Id: I15f623d82d6ec8f18b4cd4acb278873390be26cc
Reviewed-on: https://chromium-review.googlesource.com/1229974
Commit-Queue: Mythri Alle <8217f39113e9154bc3569f26a6f1ff5840cea8d8@chromium.org>
Reviewed-by: Mythri Alle <8217f39113e9154bc3569f26a6f1ff5840cea8d8@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult