Expose a lower bound of malloc'd memory via heap statistics

tools/parser-shell.cc

Index: tools/parser-shell.cc
diff --git a/tools/parser-shell.cc b/tools/parser-shell.cc
index 5d4b0cc490d2c7e2e36761e3ab3769ebca9f8cab..ad687c9efea1282d0ba07777edafc0fd282dd9d8 100644
--- a/tools/parser-shell.cc
+++ b/tools/parser-shell.cc
@@ -102,7 +102,7 @@ std::pair<v8::base::TimeDelta, v8::base::TimeDelta> RunBaselineParser(
   i::ScriptData* cached_data_impl = NULL;
   // First round of parsing (produce data to cache).
   {
-    Zone zone;
+    Zone zone(reinterpret_cast<i::Isolate*>(isolate)->allocator());
     ParseInfo info(&zone, script);
     info.set_global();
     info.set_cached_data(&cached_data_impl);
@@ -120,7 +120,7 @@ std::pair<v8::base::TimeDelta, v8::base::TimeDelta> RunBaselineParser(
   }
   // Second round of parsing (consume cached data).
   {
-    Zone zone;
+    Zone zone(reinterpret_cast<i::Isolate*>(isolate)->allocator());
     ParseInfo info(&zone, script);
     info.set_global();
     info.set_cached_data(&cached_data_impl);