Fix -Wsign-compare bugs with GCC 4.9.2

src/compiler/register-allocator.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/adapters.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/register-allocator.h"
 #include "src/string-stream.h"
 
 namespace v8 {
@@ skipping 2200 matching lines @@
 
   unsigned use_count = 0;
   auto* pos = range->first_pos();
   while (pos != nullptr) {
     use_count++;
     pos = pos->next();
   }
 
   // GetLiveRangeSize is DCHECK-ed to not be 0
   unsigned range_size = GetLiveRangeSize(range);
-  DCHECK_NE(0, range_size);
+  DCHECK_NE(0U, range_size);
 
   return static_cast<float>(use_count) / static_cast<float>(range_size);
 }
 
 
 float GreedyAllocator::CalculateMaxSpillWeight(
     const ZoneSet<LiveRange*>& ranges) {
   float max = 0.0;
   for (auto* r : ranges) {
     max = std::max(max, CalculateSpillWeight(r));
@@ skipping 609 matching lines @@
     auto eliminate = moves->PrepareInsertAfter(move);
     to_insert.push_back(move);
     if (eliminate != nullptr) to_eliminate.push_back(eliminate);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8