AK: Vector::resize() should initialize new slots for primitive types

We call placement new for the newly added slots. However, we should
also specify an initializer so primitive data types like u64 are
initialized appropriately.

AK/Vector.h

@@ -619,7 +619,7 @@ public:
             return false;
 
         for (size_t i = size(); i < new_size; ++i)
-            new (slot(i)) T;
+            new (slot(i)) T {};
         m_size = new_size;
         return true;
     }