Fix another -Wsign-compare bug with GCC 4.9.2.

src/api.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/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 6918 matching lines @@
   if (!i::FLAG_track_gc_object_stats) return false;
 
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
   i::Heap* heap = isolate->heap();
   const char* object_type;
   const char* object_sub_type;
   size_t object_count = heap->object_count_last_gc(type_index);
   size_t object_size = heap->object_size_last_gc(type_index);
   if (!heap->GetObjectTypeName(type_index, &object_type, &object_sub_type)) {
     // There should be no objects counted when the type is unknown.
-    DCHECK_EQ(object_count, 0);
-    DCHECK_EQ(object_size, 0);
+    DCHECK_EQ(object_count, 0U);
+    DCHECK_EQ(object_size, 0U);
     return false;
   }
 
   object_statistics->object_type_ = object_type;
   object_statistics->object_sub_type_ = object_sub_type;
   object_statistics->object_count_ = object_count;
   object_statistics->object_size_ = object_size;
   return true;
 }
 
@@ skipping 1120 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal