Replaced different means of zone pooling/reusing by one zone segment pool

src/runtime/runtime-strings.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/regexp/jsregexp-inl.h"
 #include "src/string-builder.h"
 #include "src/string-search.h"
@@ skipping 247 matching lines @@
   CONVERT_ARG_HANDLE_CHECKED(JSRegExp, regexp, 1);
   CONVERT_ARG_HANDLE_CHECKED(JSArray, regexp_info, 2);
 
   CHECK(regexp_info->HasFastObjectElements());
 
   RegExpImpl::GlobalCache global_cache(regexp, subject, isolate);
   if (global_cache.HasException()) return isolate->heap()->exception();
 
   int capture_count = regexp->CaptureCount();
 
-  ZoneScope zone_scope(isolate->runtime_zone());
-  ZoneList<int> offsets(8, zone_scope.zone());
+  Zone zone(isolate->allocator());
+  ZoneList<int> offsets(8, &zone);
 
   while (true) {
     int32_t* match = global_cache.FetchNext();
     if (match == NULL) break;
-    offsets.Add(match[0], zone_scope.zone());  // start
-    offsets.Add(match[1], zone_scope.zone());  // end
+    offsets.Add(match[0], &zone);  // start
+    offsets.Add(match[1], &zone);  // end
   }
 
   if (global_cache.HasException()) return isolate->heap()->exception();
 
   if (offsets.length() == 0) {
     // Not a single match.
     return isolate->heap()->null_value();
   }
 
   RegExpImpl::SetLastMatchInfo(regexp_info, subject, capture_count,
@@ skipping 844 matching lines @@
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
   if (!args[0]->IsString()) return isolate->heap()->undefined_value();
   if (!args[1]->IsNumber()) return isolate->heap()->undefined_value();
   if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value();
   return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
 }
 
 }  // namespace internal
 }  // namespace v8