Introduce FeedbackVectorSlot type - better than int.

src/full-codegen.h

 // Copyright 2012 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.
 
 #ifndef V8_FULL_CODEGEN_H_
 #define V8_FULL_CODEGEN_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
@@ skipping 414 matching lines @@
 
   // Bailout support.
   void PrepareForBailout(Expression* node, State state);
   void PrepareForBailoutForId(BailoutId id, State state);
 
   // Feedback slot support. The feedback vector will be cleared during gc and
   // collected by the type-feedback oracle.
   Handle<FixedArray> FeedbackVector() {
     return info_->feedback_vector();
   }
-  void EnsureSlotContainsAllocationSite(int slot);
+  void EnsureSlotContainsAllocationSite(FeedbackVectorSlot slot);
+  Smi* SmiFromSlot(FeedbackVectorSlot slot) const {
+    return Smi::FromInt(slot.ToInt());
+  }
 
   // Record a call's return site offset, used to rebuild the frame if the
   // called function was inlined at the site.
   void RecordJSReturnSite(Call* call);
 
   // Prepare for bailout before a test (or compare) and branch.  If
   // should_normalize, then the following comparison will not handle the
   // canonical JS true value so we will insert a (dead) test against true at
   // the actual bailout target from the optimized code. If not
   // should_normalize, the true and false labels are ignored.
@@ skipping 534 matching lines @@
 
   Address start_;
   Address instruction_start_;
   uint32_t length_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_