Fix materialization of captured objects with field tracking.

R=titzer@chromium.org
BUG=chromium:298990
TEST=mjsunit/compiler/escape-analysis-representation

Review URL: https://codereview.chromium.org/35133003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17321 ce2b1a6d-e550-0410-aec6-3dcde31c8c00