Fix bug 73940.
I think this actually turns the code in question into dead code, because the current definition of UseSparseVariant only allows arrays in DictionaryMode, and these never return encoded ranges from %GetArrayKeys. This is a subtle link between the definition of %GetArrayKeys and UseSparseVariant, so I would prefer to keep the code rather than having an invisible depeendency.
BUG=73940
Review URL: http://codereview.chromium.org/6596004
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6946
ce2b1a6d-e550-0410-aec6-
3dcde31c8c00