Initial real implementation of simple merge for frames. Does not yet...

src/register-allocator-ia32.h

Index: src/register-allocator-ia32.h
===================================================================
--- src/register-allocator-ia32.h	(revision 894)
+++ src/register-allocator-ia32.h	(working copy)
@@ -101,6 +101,10 @@
   // Allocate a free register if possible or fail by returning no_reg.
   Register Allocate();
 
+  // Allocate a free register without spilling any or fail and return
+  // no_reg.
+  Register AllocateWithoutSpilling();
+
  private:
   CodeGenerator* code_generator_;
   RegisterFile registers_;