Remove code handling parameters rewritten to properties (aka synthetic properties).

src/hydrogen.cc

 // Copyright 2011 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 5056 matching lines @@
     CHECK_ALIVE(VisitForEffect(expr->expression()));
     return ast_context()->ReturnValue(graph()->GetConstantTrue());
   } else if (var != NULL &&
              !var->is_global() &&
              var->AsSlot() != NULL &&
              var->AsSlot()->type() != Slot::LOOKUP) {
     // Result of deleting non-global, non-dynamic variables is false.
     // The subexpression does not have side effects.
     return ast_context()->ReturnValue(graph()->GetConstantFalse());
   } else if (prop != NULL) {
-    if (prop->is_synthetic()) {
-      // Result of deleting parameters is false, even when they rewrite
-      // to accesses on the arguments object.
-      return ast_context()->ReturnValue(graph()->GetConstantFalse());
-  } else {
-      CHECK_ALIVE(VisitForValue(prop->obj()));
-      CHECK_ALIVE(VisitForValue(prop->key()));
-      HValue* key = Pop();
-      HValue* obj = Pop();
-      HValue* context = environment()->LookupContext();
-      HDeleteProperty* instr = new(zone()) HDeleteProperty(context, obj, key);
-      return ast_context()->ReturnInstruction(instr, expr->id());
-    }
+    CHECK_ALIVE(VisitForValue(prop->obj()));
+    CHECK_ALIVE(VisitForValue(prop->key()));
+    HValue* key = Pop();
+    HValue* obj = Pop();
+    HValue* context = environment()->LookupContext();
+    HDeleteProperty* instr = new(zone()) HDeleteProperty(context, obj, key);
+    return ast_context()->ReturnInstruction(instr, expr->id());
   } else if (var->is_global()) {
     Bailout("delete with global variable");
   } else {
     Bailout("delete with non-global variable");
   }
 }
 
 
 void HGraphBuilder::VisitVoid(UnaryOperation* expr) {
   CHECK_ALIVE(VisitForEffect(expr->expression()));
@@ skipping 1651 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal