Tentative implementation of string slices (hidden under the flag --string-slices).

src/objects-visiting.cc

Index: src/objects-visiting.cc
diff --git a/src/objects-visiting.cc b/src/objects-visiting.cc
index 4cd795e9c07138631c67349d947ba86a19acb598..187245bbed3489cf3d65f74816e5c6de20c3e3b6 100644
--- a/src/objects-visiting.cc
+++ b/src/objects-visiting.cc
@@ -58,6 +58,9 @@ StaticVisitorBase::VisitorId StaticVisitorBase::GetVisitorId(
           return kVisitConsString;
         }
 
+      case kSlicedStringTag:
+        return kVisitSlicedString;
+
       case kExternalStringTag:
         return GetVisitorIdForSize(kVisitDataObject,
                                    kVisitDataObjectGeneric,