"Reland "Allow ICs to be generated for own global proxy.""

Causing ClusterFuzz crash (issue 343928)

TBR=verwaest@chromium.org

Review URL: https://codereview.chromium.org/179643003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19540 ce2b1a6d-e550-0410-aec6-3dcde31c8c00