Replace LoadElementsKind with LoadElementsKindFromMap, remove unneeded TODO in
DoStringCharFromCode, improve constraints for DoCheckValue and improve code for
ElementsKind checking in StoreArrayLiteralElementStub.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/202853005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20039 ce2b1a6d-e550-0410-aec6-3dcde31c8c00