This is a little experiment to move Failure to a superclass above Object...

src/accessors.cc

Index: src/accessors.cc
===================================================================
--- src/accessors.cc	(revision 5559)
+++ src/accessors.cc	(working copy)
@@ -441,11 +441,15 @@
   bool found_it = false;
   JSFunction* function = FindInPrototypeChain<JSFunction>(object, &found_it);
   if (!found_it) return Heap::undefined_value();
+    Object* prototype;
+    { TryAllocation t = Heap::AllocateFunctionPrototype(function);
+      if (!t->ToObject(&prototype)) return t;
+    }
   if (!function->has_prototype()) {
-    Object* prototype = Heap::AllocateFunctionPrototype(function);
-    if (prototype->IsFailure()) return prototype;
-    Object* result = function->SetPrototype(prototype);
-    if (result->IsFailure()) return result;
+    Object* result;
+    { TryAllocation t = function->SetPrototype(prototype);
+      if (!t->ToObject(&result)) return t;
+    }
   }
   return function->prototype();
 }
@@ -459,13 +463,17 @@
   if (!found_it) return Heap::undefined_value();
   if (function->has_initial_map()) {
     // If the function has allocated the initial map
+    Object* new_map;
+    { TryAllocation t = function->initial_map()->CopyDropTransitions();
+      if (!t->ToObject(&new_map)) return t;
+    }
     // replace it with a copy containing the new prototype.
-    Object* new_map = function->initial_map()->CopyDropTransitions();
-    if (new_map->IsFailure()) return new_map;
     function->set_initial_map(Map::cast(new_map));
+  Object* prototype;
+  { TryAllocation t = function->SetPrototype(value);
+    if (!t->ToObject(&prototype)) return t;
   }
-  Object* prototype = function->SetPrototype(value);
-  if (prototype->IsFailure()) return prototype;
+  }
   ASSERT(function->prototype() == value);
   return function;
 }