Fix double-boxing issue when materializing captured objects.
Fix double-boxing issue when materializing captured objects.

R=verwaest@chromium.org
TEST=mjsunit/compiler/escape-analysis-representation

Review URL: https://codereview.chromium.org/57783003

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@17468 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh