[runtime] Remove useless DELETE builtin.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index d351c819860a63c5d40e65a6707b58314761a227..eda5207026b8fdff1484eb837f9252ace5646311 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -4566,8 +4566,10 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
       if (property != NULL) {
         VisitForStackValue(property->obj());
         VisitForStackValue(property->key());
-        __ Push(Smi::FromInt(language_mode()));
-        __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION);
+        __ CallRuntime(is_strict(language_mode())
+                           ? Runtime::kDeleteProperty_Strict
+                           : Runtime::kDeleteProperty_Sloppy,
+                       2);
         context()->Plug(rax);
       } else if (proxy != NULL) {
         Variable* var = proxy->var();
@@ -4578,8 +4580,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         if (var->IsUnallocatedOrGlobalSlot()) {
           __ Push(GlobalObjectOperand());
           __ Push(var->name());
-          __ Push(Smi::FromInt(SLOPPY));
-          __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION);
+          __ CallRuntime(Runtime::kDeleteProperty_Sloppy, 2);
           context()->Plug(rax);
         } else if (var->IsStackAllocated() || var->IsContextSlot()) {
           // Result of deleting non-global variables is false.  'this' is