Automatically expand allocation functions with one caller

Allocation stack traces are automatically expanded until first node with several callers.

BUG=277984
R=alph@chromium.org

Review URL: https://codereview.chromium.org/25995002

git-svn-id: svn://svn.chromium.org/blink/trunk@158925 bbb929c8-8fbe-4397-9dbb-9b2b20218538