[turbofan] Fix typing rule for CheckBounds.

src/compiler/typer.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/typer.h"
 
 #include <iomanip>
 
 #include "src/base/flags.h"
 #include "src/bootstrapper.h"
@@ skipping 1792 matching lines @@
   return TypeUnaryOp(node, StringFromCodePointTyper);
 }
 
 Type* Typer::Visitor::TypeStringIndexOf(Node* node) {
   return Type::Range(-1.0, String::kMaxLength - 1.0, zone());
 }
 
 Type* Typer::Visitor::TypeCheckBounds(Node* node) {
   Type* index = Operand(node, 0);
   Type* length = Operand(node, 1);
+  if (index->Maybe(Type::MinusZero())) {
+    index = Type::Union(index, typer_->cache_.kSingletonZero, zone());
+  }
   index = Type::Intersect(index, Type::Integral32(), zone());
   if (!index->IsInhabited() || !length->IsInhabited()) return Type::None();
   double min = std::max(index->Min(), 0.0);
   double max = std::min(index->Max(), length->Max() - 1);
   if (max < min) return Type::None();
   return Type::Range(min, max, zone());
 }
 
 Type* Typer::Visitor::TypeCheckHeapObject(Node* node) {
   Type* type = Operand(node, 0);
@@ skipping 174 matching lines @@
 Type* Typer::Visitor::TypeConstant(Handle<Object> value) {
   if (Type::IsInteger(*value)) {
     return Type::Range(value->Number(), value->Number(), zone());
   }
   return Type::NewConstant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8