This reverts the part of r21154 that introduced the CHECK()s to verify
state of objects with stable maps during code generation. The CHECK()s
seem to trigger a non-critical hidden bug in the map stability
mechanism. We will re-add these CHECK()s once the bug is found and
fixed.

BUG=372173
LOG=y
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/287363002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21352 ce2b1a6d-e550-0410-aec6-3dcde31c8c00