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

src/isolate.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/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 1954 matching lines @@
       stack_trace_for_uncaught_exceptions_frame_limit_(0),
       stack_trace_for_uncaught_exceptions_options_(StackTrace::kOverview),
       keyed_lookup_cache_(NULL),
       context_slot_cache_(NULL),
       descriptor_lookup_cache_(NULL),
       handle_scope_implementer_(NULL),
       unicode_cache_(NULL),
       allocator_(FLAG_trace_gc_object_stats
                      ? new VerboseAccountingAllocator(&heap_, 256 * KB)
                      : new AccountingAllocator()),
-      runtime_zone_(new Zone(allocator_)),
       inner_pointer_to_code_cache_(NULL),
       global_handles_(NULL),
       eternal_handles_(NULL),
       thread_manager_(NULL),
       has_installed_extensions_(false),
       regexp_stack_(NULL),
       date_cache_(NULL),
       call_descriptor_data_(NULL),
       // TODO(bmeurer) Initialized lazily because it depends on flags; can
       // be fixed once the default isolate cleanup is done.
@@ skipping 252 matching lines @@
 
   delete random_number_generator_;
   random_number_generator_ = NULL;
 
   delete debug_;
   debug_ = NULL;
 
   delete cancelable_task_manager_;
   cancelable_task_manager_ = nullptr;
 
-  delete runtime_zone_;
-  runtime_zone_ = nullptr;
-
   delete allocator_;
   allocator_ = nullptr;
 
 #if USE_SIMULATOR
   Simulator::TearDown(simulator_i_cache_, simulator_redirection_);
   simulator_i_cache_ = nullptr;
   simulator_redirection_ = nullptr;
 #endif
 }
 
@@ skipping 953 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8