[turbofan] Improve typed lowering for JSToBoolean.

src/compiler/access-builder.h

Index: src/compiler/access-builder.h
diff --git a/src/compiler/access-builder.h b/src/compiler/access-builder.h
index 73c81ef106123590e3bdcddd78eecc3d178fae6b..4c22efa6ff3f07cd5a564153f64a4fb0f960591e 100644
--- a/src/compiler/access-builder.h
+++ b/src/compiler/access-builder.h
@@ -37,6 +37,9 @@ class AccessBuilder FINAL : public AllStatic {
   // 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();