Refactor assignment in the ARM code generator

Refactor assignment in the ARM code generator

This is mainly a port of r3899. It also adds handling of initilization blocks in ARM which had no special handling before.

The "calling conventions" used for

  EmitNamedLoad
  EmitNamedStore
  EmitKeyedLoad
  EmitKeyedStore

are somewhat mixed, but will become more aligned as the use of register allication and passing of argument in registers to IC's is extended.
Review URL: http://codereview.chromium.org/1846002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4574 ce2b1a6d-e550-0410-aec6-3dcde31c8c00