Implement in-place rehashing of HashTable.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index af0a8911c873bfeff4a74b79cca91d109ccef6a2..fff27179c3c85ca3d5f98e0cb1ef9e0f80121e8e 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3473,6 +3473,9 @@ class HashTable: public FixedArray {
   inline int FindEntry(Key key);
   int FindEntry(Isolate* isolate, Key key);
 
+  // Rehashes the table in-place.
+  void Rehash(Key key);
+
  protected:
   // Find the entry at which to insert element with the given key that
   // has the given hash value.
@@ -3519,6 +3522,13 @@ class HashTable: public FixedArray {
     return (last + number) & (size - 1);
   }
 
+  // Returns _expected_ if one of entries given by the first _probe_ probes is
+  // equal to  _expected_. Otherwise, returns the entry given by the probe
+  // number _probe_.
+  uint32_t EntryForProbe(Key key, Object* k, int probe, uint32_t expected);
+
+  void Swap(uint32_t entry1, uint32_t entry2, WriteBarrierMode mode);
+
   // Rehashes this hash-table into the new table.
   MUST_USE_RESULT MaybeObject* Rehash(HashTable* new_table, Key key);