[turbofan] Improve typed lowering for JSToBoolean.

src/compiler/access-builder.h

 // 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.
 
 #ifndef V8_COMPILER_ACCESS_BUILDER_H_
 #define V8_COMPILER_ACCESS_BUILDER_H_
 
 #include "src/compiler/simplified-operator.h"
 
 namespace v8 {
@@ skipping 19 matching lines @@
 
   // Provides access to JSArrayBuffer::backing_store() field.
   static FieldAccess ForJSArrayBufferBackingStore();
 
   // Provides access to ExternalArray::external_pointer() field.
   static FieldAccess ForExternalArrayPointer();
 
   // Provides access to Map::instance_type() field.
   static FieldAccess ForMapInstanceType();
 
+  // Provides access to String::length() field.
+  static FieldAccess ForStringLength();
+
   // Provides access to JSValue::value() field.
   static FieldAccess ForValue();
 
   // Provides access to FixedArray elements.
   static ElementAccess ForFixedArrayElement();
 
   // Provides access to Fixed{type}TypedArray and External{type}Array elements.
   static ElementAccess ForTypedArrayElement(ExternalArrayType type,
                                             bool is_external);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AccessBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_ACCESS_BUILDER_H_