Revert of Reland: Remove register index/code indirection

src/lithium-allocator.h

Index: src/lithium-allocator.h
diff --git a/src/lithium-allocator.h b/src/lithium-allocator.h
index e52feaa74d443101d341166a01030a03da6f4e1e..bd5127d66d82376555e23b0d444102b79df6faad 100644
--- a/src/lithium-allocator.h
+++ b/src/lithium-allocator.h
@@ -520,8 +520,9 @@
   ZoneList<LiveRange*> live_ranges_;
 
   // Lists of live ranges
-  EmbeddedVector<LiveRange*, Register::kNumRegisters> fixed_live_ranges_;
-  EmbeddedVector<LiveRange*, DoubleRegister::kMaxNumRegisters>
+  EmbeddedVector<LiveRange*, Register::kMaxNumAllocatableRegisters>
+      fixed_live_ranges_;
+  EmbeddedVector<LiveRange*, DoubleRegister::kMaxNumAllocatableRegisters>
       fixed_double_live_ranges_;
   ZoneList<LiveRange*> unhandled_live_ranges_;
   ZoneList<LiveRange*> active_live_ranges_;
@@ -535,7 +536,6 @@
 
   RegisterKind mode_;
   int num_registers_;
-  const int* allocatable_register_codes_;
 
   BitVector* assigned_registers_;
   BitVector* assigned_double_registers_;