Fix blink heap test that incorrectly assumed that a hash table did not
need to grow on the second addition.

R=erik.corry@gmail.com
BUG=

Review URL: https://codereview.chromium.org/146983005

git-svn-id: svn://svn.chromium.org/blink/trunk@166314 bbb929c8-8fbe-4397-9dbb-9b2b20218538