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

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 3c9123c6a164b38279d8f71dc206dddb35a75c52..4dcec2750faa7a1f1d3f99c45d58665667fe897b 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1972,6 +1972,7 @@
       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),
@@ -2244,6 +2245,9 @@
   delete cancelable_task_manager_;
   cancelable_task_manager_ = nullptr;
 
+  delete runtime_zone_;
+  runtime_zone_ = nullptr;
+
   delete allocator_;
   allocator_ = nullptr;