AK: Defer to Traits<T> for equality comparison in container templates.

This is prep work for supporting HashMap with NonnullRefPtr<T> as values.
It's currently not possible because many HashTable functions require being
able to default-construct the value type.

AK/Vector.h

@@ -2,22 +2,24 @@
 
 #include <AK/Assertions.h>
 #include <AK/StdLibExtras.h>
+#include <AK/Traits.h>
 #include <AK/kmalloc.h>
 
 // NOTE: We can't include <initializer_list> during the toolchain bootstrap,
 //       since it's part of libstdc++, and libstdc++ depends on LibC.
 //       For this reason, we don't support Vector(initializer_list) in LibC.
 #ifndef SERENITY_LIBC_BUILD
-#include <initializer_list>
+#    include <initializer_list>
 #endif
 
 #ifndef __serenity__
-#include <new>
+#    include <new>
 #endif
 
 namespace AK {
 
-template<typename T, int inline_capacity> class Vector;
+template<typename T, int inline_capacity>
+class Vector;
 
 template<typename VectorType, typename ElementType>
 class VectorIterator {
@@ -148,7 +150,7 @@ public:
     bool contains_slow(const T& value) const
     {
         for (int i = 0; i < size(); ++i) {
-            if (at(i) == value)
+            if (Traits<T>::equals(at(i), value))
                 return true;
         }
         return false;