Port r19976 (73bbd7a)

Original commit message:
This is required by the spec. It also prevents crashes resulting from the attempt to read type feedback for the RHS of an invalid assignment which full codegen never actually allocated info for.

To do: check properly in preparser already.

BUG=351658
LOG=Y
R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/195893031

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20004 ce2b1a6d-e550-0410-aec6-3dcde31c8c00