| Index: src/compiler/types.cc
 | 
| diff --git a/src/compiler/types.cc b/src/compiler/types.cc
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| index a2af190d9d356af94459baffcaae15e10c7f1cde..8a6484ec49132653f5225997c442cd8ffbc352f2 100644
 | 
| --- a/src/compiler/types.cc
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| +++ b/src/compiler/types.cc
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| @@ -152,6 +152,8 @@ Type::bitset BitsetType::Lub(i::Map* map) {
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|      case ONE_BYTE_STRING_TYPE:
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|      case CONS_STRING_TYPE:
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|      case CONS_ONE_BYTE_STRING_TYPE:
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| +    case THIN_STRING_TYPE:
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| +    case THIN_ONE_BYTE_STRING_TYPE:
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|      case SLICED_STRING_TYPE:
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|      case SLICED_ONE_BYTE_STRING_TYPE:
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|      case EXTERNAL_STRING_TYPE:
 | 
| 
 |