[DevTools] Profiles: search in heap profile causes exception.

It tunrs out that most profile views provide .profile member,
but CPU profile view provides .profileHeader member.

ProfilePanel should address profile uniformly ->
 renamed member in CPU profile view.

Caused by: https://codereview.chromium.org/14465004

Review URL: https://chromiumcodereview.appspot.com/18842003

git-svn-id: svn://svn.chromium.org/blink/trunk@154088 bbb929c8-8fbe-4397-9dbb-9b2b20218538