Introduce FeedbackVectorSlot type - better than int.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-properties.h"
@@ skipping 1693 matching lines @@
   compare_if.End();
   ast_context()->ReplaceValue();
 }
 
 
 StrictMode AstGraphBuilder::strict_mode() const {
   return info()->strict_mode();
 }
 
 
-VectorSlotPair AstGraphBuilder::CreateVectorSlotPair(int slot) const {
+VectorSlotPair AstGraphBuilder::CreateVectorSlotPair(
+    FeedbackVectorSlot slot) const {
   return VectorSlotPair(handle(info()->shared_info()->feedback_vector()), slot);
 }
 
 
 Node* AstGraphBuilder::ProcessArguments(const Operator* op, int arity) {
   DCHECK(environment()->stack_height() >= arity);
   Node** all = info()->zone()->NewArray<Node*>(arity);
   for (int i = arity - 1; i >= 0; --i) {
     all[i] = environment()->Pop();
   }
@@ skipping 385 matching lines @@
     DCHECK(NodeProperties::GetFrameStateInput(node)->opcode() ==
            IrOpcode::kDead);
     NodeProperties::ReplaceFrameStateInput(
         node, environment()->Checkpoint(ast_id, combine));
   }
 }
 
 }
 }
 }  // namespace v8::internal::compiler