AK: Remove a redundant double find-call in HashMap::ensure

If the value was found there's no reason to search for it again.

AK/HashMap.h

@@ -134,18 +134,21 @@ class HashMap {
  V& ensure(const K& key)
  {
  auto it = find(key);
- if (it == end())
- set(key, V());
+ if (it != end())
+ return it->value;
+ auto result = set(key, V());
+ VERIFY(result == HashSetResult::InsertedNewEntry);
  return find(key)->value;
  }
 
  template<typename Callback>
  V& ensure(K const& key, Callback initialization_callback)
  {
  auto it = find(key);
- if (it == end()) {
- set(key, initialization_callback());
- }
+ if (it != end())
+ return it->value;
+ auto result = set(key, initialization_callback());
+ VERIFY(result == HashSetResult::InsertedNewEntry);
  return find(key)->value;
  }