Revert of Internalize strings in-place

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 4a7ba35e42be1346c6db0f96909af7db1ed38f1e..b8d9166cb7e3d342e6d4e886d70bb74daf2d3679 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -100,8 +100,6 @@
   V(Map, string_map, StringMap)                                                \
   V(Map, cons_one_byte_string_map, ConsOneByteStringMap)                       \
   V(Map, cons_string_map, ConsStringMap)                                       \
-  V(Map, thin_one_byte_string_map, ThinOneByteStringMap)                       \
-  V(Map, thin_string_map, ThinStringMap)                                       \
   V(Map, sliced_string_map, SlicedStringMap)                                   \
   V(Map, sliced_one_byte_string_map, SlicedOneByteStringMap)                   \
   V(Map, external_string_map, ExternalStringMap)                               \
@@ -2120,6 +2118,10 @@
   MUST_USE_RESULT AllocationResult
       AllocateCode(int object_size, bool immovable);
 
+  MUST_USE_RESULT AllocationResult InternalizeStringWithKey(HashTableKey* key);
+
+  MUST_USE_RESULT AllocationResult InternalizeString(String* str);
+
   // ===========================================================================
 
   void set_force_oom(bool value) { force_oom_ = value; }