Revert "Get rid of the extra vector when setting up the orderIterator."

This reverts commit r153185

Lots of ASSERTS and timeouts.

BUG=255314
TBR=ojan

Review URL: https://codereview.chromium.org/18063009

git-svn-id: svn://svn.chromium.org/blink/trunk@153186 bbb929c8-8fbe-4397-9dbb-9b2b20218538