Introduce {FAST,SLOW}_STRING_WRAPPER_ELEMENTS

src/elements-kind.cc

Index: src/elements-kind.cc
diff --git a/src/elements-kind.cc b/src/elements-kind.cc
index 0d29c3047238cbcfe6b0df71b196441686fa3e48..7bb75c4c9c63d69fd7d0c3e2bf24ccb9d67f8324 100644
--- a/src/elements-kind.cc
+++ b/src/elements-kind.cc
@@ -37,7 +37,12 @@ int ElementsKindToShiftSize(ElementsKind elements_kind) {
     case DICTIONARY_ELEMENTS:
     case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
     case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
+    case FAST_STRING_WRAPPER_ELEMENTS:
+    case SLOW_STRING_WRAPPER_ELEMENTS:
       return kPointerSizeLog2;
+    case NO_ELEMENTS:
+      UNREACHABLE();
+      return 0;
   }
   UNREACHABLE();
   return 0;