Issue 6279 - Make HashContainer movable and optimize resizing by moving entries.

compiled/StringMap.h

Index: compiled/StringMap.h
===================================================================
--- a/compiled/StringMap.h
+++ b/compiled/StringMap.h
@@ -48,16 +48,20 @@
   struct StringSetEntry
   {
     typedef Key key_type;
     typedef const String& key_type_cref;
     typedef size_t size_type;
 
     key_type first;
 
+    StringSetEntry& operator=(const StringSetEntry&) = default;
+    StringSetEntry& operator=(StringSetEntry&&) = default;
+
+    StringSetEntry(const StringSetEntry&) = default;
     StringSetEntry(key_type_cref key = key_type())
     {
       if (!key.is_invalid())
         first.reset(key);
     }
 
     bool equals(key_type_cref other) const
     {
@@ -88,19 +92,22 @@
   template<typename Key, typename Value>
   struct StringMapEntry : StringSetEntry<Key>
   {
     typedef StringSetEntry<Key> super;
     typedef Value value_type;
 
     value_type second;
 
+    StringMapEntry& operator=(const StringMapEntry&) = default;
+    StringMapEntry& operator=(StringMapEntry&&) = default;
+
     StringMapEntry(typename super::key_type_cref key = Key(),
                    value_type value = value_type())
-        : super(key), second(value)
+       : super(key), second(std::move(value))
     {
     }
 
     void erase()
     {
       super::erase();
       second = value_type();
     }