Strict mode delete.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index fe9056709cdd4386340c9987f9016d25bc244bc2..a6b81191a00da398729f633bb5137ea3aa272ec9 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -7230,19 +7230,22 @@ void CodeGenerator::VisitUnaryOperation(UnaryOperation* node) {
     if (property != NULL) {
       Load(property->obj());
       Load(property->key());
-      Result answer = frame_->InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, 2);
+      frame_->Push(Smi::FromInt(strict_mode_flag()));
+      Result answer = frame_->InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, 3);
       frame_->Push(&answer);
       return;
     }
 
     Variable* variable = node->expression()->AsVariableProxy()->AsVariable();
     if (variable != NULL) {
+      ASSERT(strict_mode_flag() == kNonStrictMode);
       Slot* slot = variable->AsSlot();
       if (variable->is_global()) {
         LoadGlobal();
         frame_->Push(variable->name());
+        frame_->Push(Smi::FromInt(kNonStrictMode));
         Result answer = frame_->InvokeBuiltin(Builtins::DELETE,
-                                              CALL_FUNCTION, 2);
+                                              CALL_FUNCTION, 3);
         frame_->Push(&answer);
         return;