Remove unnecessary explicity prototype check.

src/x64/stub-cache-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1059 matching lines @@
 
 
 void BaseLoadStubCompiler::NonexistentHandlerFrontend(
     Handle<JSObject> object,
     Handle<JSObject> last,
     Handle<Name> name,
     Label* success,
     Handle<GlobalObject> global) {
   Label miss;
 
-  Register reg = HandlerFrontendHeader(object, receiver(), last, name, &miss);
+  HandlerFrontendHeader(object, receiver(), last, name, &miss);
 
   // If the last object in the prototype chain is a global object,
   // check that the global property cell is empty.
   if (!global.is_null()) {
     GenerateCheckPropertyCell(masm(), global, name, scratch2(), &miss);
   }
 
-  if (!last->HasFastProperties()) {
-    __ movq(scratch2(), FieldOperand(reg, HeapObject::kMapOffset));
-    __ movq(scratch2(), FieldOperand(scratch2(), Map::kPrototypeOffset));
-    __ Cmp(scratch2(), isolate()->factory()->null_value());
-    __ j(not_equal, &miss);
-  }
-
   HandlerFrontendFooter(success, &miss);
 }
 
 
 void BaseLoadStubCompiler::GenerateLoadField(Register reg,
                                              Handle<JSObject> holder,
                                              PropertyIndex index) {
   // Get the value from the properties.
   GenerateFastPropertyLoad(masm(), rax, reg, holder, index);
   __ ret(0);
@@ skipping 2309 matching lines @@
     TailCallBuiltin(masm, Builtins::kKeyedStoreIC_Slow);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64