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 83879215fc3720185b5cd637806f0421b475befc..c50ae272916d70ea386fc9e37ccd23e0fd41d029 100644
--- a/src/ast/ast-types.cc
+++ b/src/ast/ast-types.cc
@@ -157,6 +157,8 @@ 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: