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 dff7f9e7d9808d6ad76ee7820365f2ffb5abbe40..8b800ae93b31b4dfeafdb8fcf4c68b231b1d767c 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -101,8 +101,6 @@ using v8::MemoryPressureLevel;
   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)                               \
@@ -2133,6 +2131,10 @@ class Heap {
   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; }