Fix more -Werror=sign-compare bugs with GCC 4.9.2

src/heap/identity-map.cc

 // Copyright 2015 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/v8.h"
 
 #include "src/heap/heap.h"
 #include "src/heap/identity-map.h"
 
 namespace v8 {
@@ skipping 20 matching lines @@
 IdentityMapBase::RawEntry IdentityMapBase::Insert(Handle<Object> key) {
   AllowHandleDereference for_lookup;
   int index = InsertIndex(*key);
   DCHECK_GE(index, 0);
   return &values_[index];
 }
 
 
 int IdentityMapBase::Hash(Object* address) {
   uintptr_t raw_address = reinterpret_cast<uintptr_t>(address);
-  CHECK_NE(0, raw_address);  // Cannot store Smi 0 as a key here, sorry.
+  CHECK_NE(0U, raw_address);  // Cannot store Smi 0 as a key here, sorry.
   // Xor some of the upper bits, since the lower 2 or 3 are usually aligned.
   return static_cast<int>((raw_address >> 11) ^ raw_address);
 }
 
 
 int IdentityMapBase::LookupIndex(Object* address) {
   int start = Hash(address) & mask_;
   for (int index = start; index < size_; index++) {
     if (keys_[index] == address) return index;  // Found.
     if (keys_[index] == nullptr) return -1;     // Not found.
@@ skipping 130 matching lines @@
     DCHECK_GE(index, 0);
     values_[index] = old_values[i];
   }
 
   // Unregister old keys and register new keys.
   heap_->UnregisterStrongRoots(old_keys);
   heap_->RegisterStrongRoots(keys_, keys_ + size_);
 }
 }
 }  // namespace v8::internal