Add inline caches for loading non-existing properties.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
===================================================================
--- src/x64/stub-cache-x64.cc	(revision 4394)
+++ src/x64/stub-cache-x64.cc	(working copy)
@@ -1144,6 +1144,36 @@
 }
 
 
+Object* LoadStubCompiler::CompileLoadNonExisting(JSObject* object) {
+  // ----------- S t a t e -------------
+  //  -- rcx    : name
+  //  -- rsp[0] : return address
+  //  -- rsp[8] : receiver
+  // -----------------------------------
+  Label miss;
+
+  // Load receiver.
+  __ movq(rax, Operand(rsp, kPointerSize));
+
+  // Check the maps of the full prototype chain.
+  JSObject* last = object;
+  while (last->GetPrototype() != Heap::null_value()) {
+    last = JSObject::cast(last->GetPrototype());
+  }
+  CheckPrototypes(object, rax, last, rbx, rdx, Heap::empty_string(), &miss);
+
+  // Return undefined if maps of the full prototype chain is still the same.
+  __ LoadRoot(rax, Heap::kUndefinedValueRootIndex);
+  __ ret(0);
+
+  __ bind(&miss);
+  GenerateLoadMiss(masm(), Code::LOAD_IC);
+
+  // Return the generated code.
+  return GetCode(NON_EXISTING, Heap::empty_string());
+}
+
+
 Object* LoadStubCompiler::CompileLoadField(JSObject* object,
                                            JSObject* holder,
                                            int index,