Fix X64 build in the case that debugger support is disabled.  Change function name from IsCallInstruction to IsPatchedReturnSequence on all platforms.
Review URL: http://codereview.chromium.org/267116

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3072 ce2b1a6d-e550-0410-aec6-3dcde31c8c00