Revert accidental change from r7795 that was causing a bug fixed in r7790 to reappear.

src/x64/code-stubs-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 992 matching lines @@
         __ movq(FieldOperand(rax, HeapObject::kMapOffset),
                 heap_number_map);
         __ cvtqsi2sd(xmm0, rbx);
         __ movsd(FieldOperand(rax, HeapNumber::kValueOffset), xmm0);
         __ Ret();
 
         __ bind(&allocation_failed);
         // We need tagged values in rdx and rax for the following code,
         // not int32 in rax and rcx.
         __ Integer32ToSmi(rax, rcx);
-        __ Integer32ToSmi(rdx, rax);
+        __ Integer32ToSmi(rdx, rbx);
         __ jmp(allocation_failure);
       }
       break;
     }
     default: UNREACHABLE(); break;
   }
   // No fall-through from this generated code.
   if (FLAG_debug_code) {
     __ Abort("Unexpected fall-through in "
              "TypeRecordingBinaryStub::GenerateFloatingPointCode.");
@@ skipping 4098 matching lines @@
   __ Drop(1);
   __ ret(2 * kPointerSize);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64