- Simplify the switch statement code generation.
- Ensure that the switch value is always popped from the stack.

Credit goes to Feng for isolating the issue and proposing a fix.
Review URL: http://codereview.chromium.org/2888

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@315 ce2b1a6d-e550-0410-aec6-3dcde31c8c00