Internalize strings in-place

src/ast/ast-types.cc

Index: src/ast/ast-types.cc
diff --git a/src/ast/ast-types.cc b/src/ast/ast-types.cc
index 8e1cca20301a9a0e59929c4c84531cd5e7207e44..d8e9effb0325a2f2ee6e81233642b84ee13e3d0b 100644
--- a/src/ast/ast-types.cc
+++ b/src/ast/ast-types.cc
@@ -156,6 +156,8 @@ AstType::bitset AstBitsetType::Lub(i::Map* map) {
     case ONE_BYTE_STRING_TYPE:
     case CONS_STRING_TYPE:
     case CONS_ONE_BYTE_STRING_TYPE:
+    case THIN_STRING_TYPE:
+    case THIN_ONE_BYTE_STRING_TYPE:
     case SLICED_STRING_TYPE:
     case SLICED_ONE_BYTE_STRING_TYPE:
     case EXTERNAL_STRING_TYPE: