[turbofan] Don't eliminate unused CheckFloat64Hole.

src/compiler/simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/address-map.h"
 #include "src/base/bits.h"
@@ skipping 2537 matching lines @@
       case IrOpcode::kNewUnmappedArgumentsElements: {
         ProcessRemainingInputs(node, 0);
         SetOutput(node, MachineRepresentation::kTaggedPointer);
         return;
       }
       case IrOpcode::kArrayBufferWasNeutered: {
         VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kBit);
         return;
       }
       case IrOpcode::kCheckFloat64Hole: {
-        if (truncation.IsUnused()) return VisitUnused(node);
         CheckFloat64HoleMode mode = CheckFloat64HoleModeOf(node->op());
         ProcessInput(node, 0, UseInfo::TruncatingFloat64());
         ProcessRemainingInputs(node, 1);
         SetOutput(node, MachineRepresentation::kFloat64);
         if (truncation.IsUsedAsFloat64() &&
             mode == CheckFloat64HoleMode::kAllowReturnHole) {
           if (lower()) DeferReplacement(node, node->InputAt(0));
         }
         return;
       }
@@ skipping 939 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoProperties);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8