[turbofan] Initial version of allocation folding and write barrier elimination.

src/compiler/js-generic-lowering.cc

Index: src/compiler/js-generic-lowering.cc
diff --git a/src/compiler/js-generic-lowering.cc b/src/compiler/js-generic-lowering.cc
index de167226ee5217847ff946f749c3841e066457bc..1ce9768031330d0859c261a47a29b7f1f961cc72 100644
--- a/src/compiler/js-generic-lowering.cc
+++ b/src/compiler/js-generic-lowering.cc
@@ -138,14 +138,14 @@ void JSGenericLowering::LowerJSStrictNotEqual(Node* node) {
 void JSGenericLowering::LowerJSToBoolean(Node* node) {
   Callable callable = CodeFactory::ToBoolean(isolate());
   node->AppendInput(zone(), graph()->start());
-  ReplaceWithStubCall(node, callable, CallDescriptor::kNoFlags,
+  ReplaceWithStubCall(node, callable, CallDescriptor::kNoAllocate,
                       Operator::kEliminatable);
 }
 
 void JSGenericLowering::LowerJSTypeOf(Node* node) {
   Callable callable = CodeFactory::Typeof(isolate());
   node->AppendInput(zone(), graph()->start());
-  ReplaceWithStubCall(node, callable, CallDescriptor::kNoFlags,
+  ReplaceWithStubCall(node, callable, CallDescriptor::kNoAllocate,
                       Operator::kEliminatable);
 }