Get rid of the ZoneScopeMode.

src/jsregexp.cc

Index: src/jsregexp.cc
diff --git a/src/jsregexp.cc b/src/jsregexp.cc
index 7838c04a9e2f049e7ecc046813c305fe6342d9d6..42c9bb1477b7b9361a5efb375e3ba952d195519c 100644
--- a/src/jsregexp.cc
+++ b/src/jsregexp.cc
@@ -170,7 +170,7 @@ Handle<Object> RegExpImpl::Compile(Handle<JSRegExp> re,
                                    Handle<String> pattern,
                                    Handle<String> flag_str,
                                    Zone* zone) {
-  ZoneScope zone_scope(zone, DELETE_ON_EXIT);
+  ZoneScope zone_scope(zone);
   Isolate* isolate = re->GetIsolate();
   JSRegExp::Flags flags = RegExpFlagsFromString(flag_str);
   CompilationCache* compilation_cache = isolate->compilation_cache();
@@ -410,7 +410,7 @@ bool RegExpImpl::CompileIrregexp(Handle<JSRegExp> re,
                                  bool is_ascii) {
   // Compile the RegExp.
   Isolate* isolate = re->GetIsolate();
-  ZoneScope zone_scope(isolate->runtime_zone(), DELETE_ON_EXIT);
+  ZoneScope zone_scope(isolate->runtime_zone());
   PostponeInterruptsScope postpone(isolate);
   // If we had a compilation error the last time this is saved at the
   // saved code index.