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

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
===================================================================
--- src/x64/stub-cache-x64.cc	(revision 5559)
+++ src/x64/stub-cache-x64.cc	(working copy)
@@ -800,9 +800,11 @@
                                          GlobalObject* global,
                                          String* name,
                                          Register scratch,
+  Object* probe;
+  { TryAllocation t = global->EnsurePropertyCell(name);
+    if (!t->ToObject(&probe)) return t;
+  }
                                          Label* miss) {
-  Object* probe = global->EnsurePropertyCell(name);
-  if (probe->IsFailure()) return probe;
   JSGlobalPropertyCell* cell = JSGlobalPropertyCell::cast(probe);
   ASSERT(cell->value()->IsTheHole());
   __ Move(scratch, Handle<Object>(cell));
@@ -879,9 +881,12 @@
 }
 
 
+  Object* obj;
+  { TryAllocation t =
+        StubCache::ComputeCallMiss(arguments().immediate(), kind_);
+    if (!t->ToObject(&obj)) return t;
+  }
 Object* CallStubCompiler::GenerateMissBranch() {
-  Object* obj = StubCache::ComputeCallMiss(arguments().immediate(), kind_);
-  if (obj->IsFailure()) return obj;
   __ Jump(Handle<Code>(Code::cast(obj)), RelocInfo::CODE_TARGET);
   return obj;
 }
@@ -1033,9 +1038,11 @@
   }
 
   // Handle call cache miss.
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss_in_smi_check);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(function);
@@ -1088,9 +1095,11 @@
   __ InvokeFunction(rdi, arguments(), JUMP_FUNCTION);
 
   // Handle call cache miss.
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(FIELD, name);
@@ -1246,9 +1255,11 @@
                                  1);
   }
 
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(function);
@@ -1328,9 +1339,11 @@
                                argc + 1,
                                1);
 
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(function);
@@ -1400,9 +1413,11 @@
   __ LoadRoot(rax, Heap::kEmptyStringRootIndex);
   __ ret((argc + 1) * kPointerSize);
 
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(function);
@@ -1470,9 +1485,11 @@
   __ LoadRoot(rax, Heap::kNanValueRootIndex);
   __ ret((argc + 1) * kPointerSize);
 
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(function);
@@ -1539,9 +1556,11 @@
   __ InvokeFunction(function, arguments(), JUMP_FUNCTION);
 
   __ bind(&miss);
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   // rcx: function name.
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return (cell == NULL) ? GetCode(function) : GetCode(NORMAL, name);
@@ -1652,9 +1671,11 @@
   __ InvokeFunction(function, arguments(), JUMP_FUNCTION);
 
   __ bind(&miss);
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   // rcx: function name.
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return (cell == NULL) ? GetCode(function) : GetCode(NORMAL, name);
@@ -1718,9 +1739,11 @@
   __ InvokeFunction(rdi, arguments(), JUMP_FUNCTION);
 
   // Handle load cache miss.
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(INTERCEPTOR, name);
@@ -1781,9 +1804,11 @@
 
   // Handle call cache miss.
   __ bind(&miss);
+  Object* obj;
+  { TryAllocation t = GenerateMissBranch();
+    if (!t->ToObject(&obj)) return t;
+  }
   __ IncrementCounter(&Counters::call_global_inline_miss, 1);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
 
   // Return the generated code.
   return GetCode(NORMAL, name);