[compiler] Properly guard the speculative optimizations for instanceof.

src/ast/ast.cc

 // 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.
 
 #include "src/ast/ast.h"
 
 #include <cmath>  // For isfinite.
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 717 matching lines @@
   UnaryOperation* maybe_unary = expr->AsUnaryOperation();
   return maybe_unary != NULL && maybe_unary->op() == Token::TYPEOF;
 }
 
 void CompareOperation::AssignFeedbackVectorSlots(
     Isolate* isolate, FeedbackVectorSpec* spec,
     FeedbackVectorSlotCache* cache_) {
   // Feedback vector slot is only used by interpreter for binary operations.
   // Full-codegen uses AstId to record type feedback.
   switch (op()) {
-    // instanceof and in do not collect type feedback.
     case Token::INSTANCEOF:
+      // instanceof collects feedback in a general slot (for now).
+      type_feedback_slot_ = spec->AddGeneralSlot();
+      return;
     case Token::IN:
+      // in does not collect type feedback.
       return;
     default:
       type_feedback_slot_ = spec->AddInterpreterCompareICSlot();
+      return;
   }
 }
 
 // Check for the pattern: typeof <expression> equals <string literal>.
 static bool MatchLiteralCompareTypeof(Expression* left,
                                       Token::Value op,
                                       Expression* right,
                                       Expression** expr,
                                       Handle<String>* check) {
   if (IsTypeof(left) && right->IsStringLiteral() && Token::IsEqualityOp(op)) {
@@ skipping 206 matching lines @@
 // static
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 }  // namespace internal
 }  // namespace v8