Until now we always recorded two deoptimization environments for instructions
that are marked as calls. We actually don't need two for all LIR
instructions except one (LInstanceOfKnownGlobal) where there is a lazy
deoptimization point in deferred code.

This change remove on of them and uses one virtual function instead
to make LInstanceOfKnownGlobal work as before.

Additionally, this change removes an unused predicate save_doubles_ from LIR
instructions and removes some helper functions that are used only in one place.
Review URL: https://chromiumcodereview.appspot.com/10035021

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11454 ce2b1a6d-e550-0410-aec6-3dcde31c8c00