Correct bug with left shift on X64 platform from change 4571 (http://code.google.com/p/v8/source/detail?r=4571).  Speed up left shift with a constant left hand side on X64 platform.  Add unit test for this bug.  Remove unused failure target argument from MacroAssembler::SmiShiftLeft and MacroAssembler::SmiShiftLeftConstant.
Review URL: http://codereview.chromium.org/1934004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4598 ce2b1a6d-e550-0410-aec6-3dcde31c8c00