Reland r20974: Unify and simplify the FastCloneShallowArrayStub

- Don't bake in length/capacity into full codegen calls of stubs,
allowing boilerplates to increase their capacity without regenerating
code.
- Unify all variants of the clone stub into a single,
length-independent version.
- Various tweaks to make sure that the clone stub doesn't spill and
therefore need an eager stack frame.
- Handle all lengths of array literals in the fast case.

R=mvstanton@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=21230

Review URL: https://codereview.chromium.org/272513004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21253 ce2b1a6d-e550-0410-aec6-3dcde31c8c00