blink_gc_plugin: Make RecordInfo::Get{Fields,Bases} return deterministic order

tools/clang/blink_gc_plugin/RecordInfo.cpp

 // Copyright 2014 The Chromium 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 "Config.h"
 #include "RecordInfo.h"
 
 using namespace clang;
 using std::string;
 
@@ skipping 381 matching lines @@
        it != record_->bases_end();
        ++it) {
     const CXXBaseSpecifier& spec = *it;
     RecordInfo* info = cache_->Lookup(spec.getType());
     if (!info)
       continue;
     CXXRecordDecl* base = info->record();
     TracingStatus status = info->InheritsTrace()
                                ? TracingStatus::Needed()
                                : TracingStatus::Unneeded();
-    bases->insert(std::make_pair(base, BasePoint(spec, info, status)));
+    bases->push_back(std::make_pair(base, BasePoint(spec, info, status)));
   }
   return bases;
 }
 
 RecordInfo::Fields& RecordInfo::GetFields() {
   if (!fields_)
     fields_ = CollectFields();
   return *fields_;
 }
 
@@ skipping 241 matching lines @@
         edge->members().push_back(member);
       }
       // TODO: Handle the case where we fail to create an edge (eg, if the
       // argument is a primitive type or just not fully known yet).
     }
     return edge;
   }
 
   return new Value(info);
 }