Fix gc stress builder.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/19507004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15726 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Do not materialize context-allocated values for debug-evaluate.

BUG=259300
R=ulan@chromium.org, verwaest@chromium.org

Review URL: https://codereview.chromium.org/19569003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15727 ce2b1a6d-e550-0410-aec6-3dcde31c8c00