Revert 21774: "Generate KeyedLoadGeneric with Hydrogen"

Due to arm64 and GCMole failures

TBR=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/329253003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21776 ce2b1a6d-e550-0410-aec6-3dcde31c8c00