Remove ~MaybeHandle and statically assert that handles are trivially copyable

src/handles.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/handles.h"
 
 #include "src/address-map.h"
 #include "src/base/logging.h"
 #include "src/identity-map.h"
 #include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
 
+// Handles should be trivially copyable so that they can be efficiently passed
+// by value. If they are not trivially copyable, they cannot be passed in
+// registers.
+static_assert(std::is_trivially_copyable<HandleBase>::value,
+              "HandleBase should be trivially copyable");
+static_assert(std::is_trivially_copyable<Handle<Object>>::value,
+              "Handle<Object> should be trivially copyable");
+static_assert(std::is_trivially_copyable<MaybeHandle<Object>>::value,
+              "MaybeHandle<Object> should be trivially copyable");
+
 #ifdef DEBUG
 bool HandleBase::IsDereferenceAllowed(DereferenceCheckMode mode) const {
   DCHECK_NOT_NULL(location_);
   Object* object = *location_;
   if (object->IsSmi()) return true;
   HeapObject* heap_object = HeapObject::cast(object);
   Heap* heap = heap_object->GetHeap();
   Object** roots_array_start = heap->roots_array_start();
   if (roots_array_start <= location_ &&
       location_ < roots_array_start + Heap::kStrongRootListLength &&
@@ skipping 168 matching lines @@
   data->next = prev_next_;
   data->limit = prev_limit_;
 #ifdef DEBUG
   handles_detached_ = true;
 #endif
   return deferred;
 }
 
 }  // namespace internal
 }  // namespace v8