[turbofan] Renamed the ChangeFloat64ToInt64 operator to TruncateFloat64ToInt64.

src/compiler/machine-operator.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/machine-type.h"
 
@@ skipping 184 matching lines @@
   const Operator* Uint64Mod();
 
   // These operators change the representation of numbers while preserving the
   // value of the number. Narrowing operators assume the input is representable
   // in the target type and are *not* defined for other inputs.
   // Use narrowing change operators only when there is a static guarantee that
   // the input value is representable in the target value.
   const Operator* ChangeFloat32ToFloat64();
   const Operator* ChangeFloat64ToInt32();   // narrowing
   const Operator* ChangeFloat64ToUint32();  // narrowing
-  const Operator* ChangeFloat64ToInt64();   // narrowing
+  const Operator* TruncateFloat64ToInt64();
   const Operator* TruncateFloat64ToUint64();
   const Operator* ChangeInt32ToFloat64();
   const Operator* ChangeInt32ToInt64();
   const Operator* ChangeUint32ToFloat64();
   const Operator* ChangeUint32ToUint64();
 
   // These operators truncate or round numbers, both changing the representation
   // of the number and mapping multiple input values onto the same output value.
   const Operator* TruncateFloat64ToFloat32();
   const Operator* TruncateFloat64ToInt32(TruncationMode);
@@ skipping 122 matching lines @@
 };
 
 
 DEFINE_OPERATORS_FOR_FLAGS(MachineOperatorBuilder::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_