[turbofan] Lower %_DebugIsActive intrinsic.

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 ef3cdb1041d985671b33c1b40ae815b21f039e4b..1929040b12cc1f589c718dd3594cca5a46a37765 100644
--- a/src/compiler/access-builder.h
+++ b/src/compiler/access-builder.h
@@ -26,6 +26,9 @@ class V8_EXPORT_PRIVATE AccessBuilder final
   // Provides access to a double field identified by an external reference.
   static FieldAccess ForExternalDoubleValue();
 
+  // Provides access to an uint8 field identified by an external reference.
+  static FieldAccess ForExternalUint8Value();
+
   // ===========================================================================
   // Access to heap object fields and elements (based on tagged pointer).