[ast] Clean up a few unnecessary bits in AST

src/crankshaft/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/hydrogen.h"
 
 #include <memory>
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
@@ skipping 7067 matching lines @@
       // TODO(adamk): Is this required? Legacy const variables are always
       // initialized before use.
       if (var->IsStackAllocated()) {
         // We insert a use of the old value to detect unsupported uses of const
         // variables (e.g. initialization inside a loop).
         HValue* old_value = environment()->Lookup(var);
         Add<HUseConst>(old_value);
       }
     }
 
-    if (proxy->IsArguments()) return Bailout(kAssignmentToArguments);
+    if (var->is_arguments()) return Bailout(kAssignmentToArguments);
 
     // Handle the assignment.
     switch (var->location()) {
       case VariableLocation::GLOBAL:
       case VariableLocation::UNALLOCATED:
         CHECK_ALIVE(VisitForValue(expr->value()));
         HandleGlobalVariableAssignment(var, Top(), expr->AssignmentSlot(),
                                        expr->AssignmentId());
         return ast_context()->ReturnValue(Pop());
 
@@ skipping 6333 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8