Fix LOperand aliasing bug in the register allocator, avoid splitting very short live ranges.

src/lithium-allocator.cc

Index: src/lithium-allocator.cc
===================================================================
--- src/lithium-allocator.cc	(revision 11545)
+++ src/lithium-allocator.cc	(working copy)
@@ -851,7 +851,10 @@
               zone_);
         }
 
-        AddConstraintsGapMove(gap_index, input_copy, cur_input);
+        LUnallocated* cur_input_copy = cur_input->CopyUnconstrained();
+        cur_input_copy->set_policy(cur_input->policy());
+
+        AddConstraintsGapMove(gap_index, input_copy, cur_input_copy);
       }
     }
   }
@@ -1851,7 +1854,6 @@
     return;
   }
 
-
   LifetimePosition use_pos[DoubleRegister::kNumAllocatableRegisters];
   LifetimePosition block_pos[DoubleRegister::kNumAllocatableRegisters];