Remove current profile when clearing all profiles

When all profiles are removed current "Record Object Allocations" profile will also disappear. It fixes regression introduced in r168565: current profile is preserved only in case when _reset is called as a result of HeapProfiler.resetProfiles protocol message handling.

BUG=350799
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/194623004

git-svn-id: svn://svn.chromium.org/blink/trunk@168915 bbb929c8-8fbe-4397-9dbb-9b2b20218538