Continue recording object allocation after navigation

Old profile is removed on HeapProfiler.resetProfiles message and a new one is added immediately to collect all object allocation events from the backend after navigation.

BUG=None

Review URL: https://codereview.chromium.org/172163005

git-svn-id: svn://svn.chromium.org/blink/trunk@168565 bbb929c8-8fbe-4397-9dbb-9b2b20218538