Record the key as a input operand for keyed call instructions instead
of wrongly making it a temp operand.

This bug does currently not show up as a problem because the 
uses are recorded only in the instruction summary.

Review URL: http://codereview.chromium.org/6368003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6365 ce2b1a6d-e550-0410-aec6-3dcde31c8c00