Apply object updates from the network without blowing away object identity or UI attributes.

After this change, a data update will no longer collapse any expanded sections.

BUG=408364
NOTRY=true

Review URL: https://codereview.chromium.org/526633002

git-svn-id: svn://svn.chromium.org/blink/trunk@181405 bbb929c8-8fbe-4397-9dbb-9b2b20218538