Avoid signed/unsigned warning in VC++ 2017 builds

test/unittests/base/iterator-unittest.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/base/iterator.h"
 
 #include <deque>
 
 #include "test/unittests/test-utils.h"
 
@@ skipping 24 matching lines @@
   base::iterator_range<int*> r2(&array[0], &array[0]);
   EXPECT_EQ(0, r2.size());
   EXPECT_TRUE(r2.empty());
   for (auto i : array) {
     EXPECT_EQ(r2.end(), std::find(r2.begin(), r2.end(), i));
   }
 }
 
 
 TEST(IteratorTest, IteratorRangeDeque) {
-  typedef std::deque<unsigned> C;
+  typedef std::deque<int> C;
   C c;
   c.push_back(1);
   c.push_back(2);
   c.push_back(2);
   base::iterator_range<typename C::iterator> r(c.begin(), c.end());
   EXPECT_EQ(3, r.size());
   EXPECT_FALSE(r.empty());
   EXPECT_TRUE(c.begin() == r.begin());
   EXPECT_TRUE(c.end() == r.end());
   EXPECT_EQ(0, std::count(r.begin(), r.end(), 0));
   EXPECT_EQ(1, std::count(r.begin(), r.end(), 1));
   EXPECT_EQ(2, std::count(r.begin(), r.end(), 2));
 }
 
 }  // namespace base
 }  // namespace v8