Remove unnecessary explicity prototype check.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index 7e900dbe6866f229983dc3157f39c0dee06933af..c16da0cdb62826757c20d43ded1ebafd3159a7b1 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -1077,7 +1077,7 @@ void BaseLoadStubCompiler::NonexistentHandlerFrontend(
     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.
@@ -1085,13 +1085,6 @@ void BaseLoadStubCompiler::NonexistentHandlerFrontend(
     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);
 }