[turbofan] Fix win64 after r28066.

src/compiler/js-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_JS_OPERATOR_H_
 #define V8_COMPILER_JS_OPERATOR_H_
 
 #include "src/runtime/runtime.h"
 #include "src/unique.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class Operator;
 struct JSOperatorGlobalCache;
 
 
 // Defines the arity and the call flags for a JavaScript function call. This is
 // used as a parameter by JSCallFunction operators.
 class CallFunctionParameters final {
  public:
   CallFunctionParameters(size_t arity, CallFunctionFlags flags,
                          LanguageMode language_mode)
-      : bit_field_(ArityField::encode(arity) | FlagsField::encode(flags) |
+      : bit_field_(ArityField::encode(static_cast<unsigned>(arity)) |
+                   FlagsField::encode(flags) |
                    LanguageModeField::encode(language_mode)) {}
 
   size_t arity() const { return ArityField::decode(bit_field_); }
   CallFunctionFlags flags() const { return FlagsField::decode(bit_field_); }
   LanguageMode language_mode() const {
     return LanguageModeField::decode(bit_field_);
   }
 
   bool operator==(CallFunctionParameters const& that) const {
     return this->bit_field_ == that.bit_field_;
@@ skipping 296 matching lines @@
   Zone* const zone_;
 
   DISALLOW_COPY_AND_ASSIGN(JSOperatorBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_OPERATOR_H_