[turbofan] More "auto" keyword cleanup

src/compiler/zone-pool.cc

Index: src/compiler/zone-pool.cc
diff --git a/src/compiler/zone-pool.cc b/src/compiler/zone-pool.cc
index 2006a79d2c6a9849540b9fa5ecbe2dc91afeb833..a11cdb471dda2431391d832a268d9233fceff54a 100644
--- a/src/compiler/zone-pool.cc
+++ b/src/compiler/zone-pool.cc
@@ -13,7 +13,7 @@ ZonePool::StatsScope::StatsScope(ZonePool* zone_pool)
       total_allocated_bytes_at_start_(zone_pool->GetTotalAllocatedBytes()),
       max_allocated_bytes_(0) {
   zone_pool_->stats_.push_back(this);
-  for (auto zone : zone_pool_->used_) {
+  for (Zone* zone : zone_pool_->used_) {
     size_t size = static_cast<size_t>(zone->allocation_size());
     std::pair<InitialValues::iterator, bool> res =
         initial_values_.insert(std::make_pair(zone, size));
@@ -116,7 +116,7 @@ void ZonePool::ReturnZone(Zone* zone) {
   // Update max.
   max_allocated_bytes_ = std::max(max_allocated_bytes_, current_total);
   // Update stats.
-  for (auto stat_scope : stats_) {
+  for (StatsScope* stat_scope : stats_) {
     stat_scope->ZoneReturned(zone);
   }
   // Remove from used.