Cleanup: Remove a reference to the heapchecker test framework that no longer exists.

BUG=325380
NOTRY=true

Review URL: https://codereview.chromium.org/131563006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246089 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246089