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

tools/clang/blink_gc_plugin/CheckFinalizerVisitor.cpp

 // Copyright 2015 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 "CheckFinalizerVisitor.h"
 
 using namespace clang;
 
 namespace {
 
@@ skipping 89 matching lines @@
 
 bool CheckFinalizerVisitor::VisitMemberExpr(MemberExpr* member) {
   FieldDecl* field = dyn_cast<FieldDecl>(member->getMemberDecl());
   if (!field)
     return true;
 
   RecordInfo* info = cache_->Lookup(field->getParent());
   if (!info)
     return true;
 
-  RecordInfo::Fields::iterator it = info->GetFields().find(field);
-  if (it == info->GetFields().end())
+  if (!info->HasField(field))
     return true;
 
   if (seen_members_.find(member) != seen_members_.end())
     return true;
 
   bool as_eagerly_finalized = false;
   if (blacklist_context_ &&
-      MightBeCollected(&it->second, &as_eagerly_finalized)) {
+      MightBeCollected(&info->GetField(field).second, &as_eagerly_finalized)) {
     finalized_fields_.push_back(
-        Error(member, as_eagerly_finalized, &it->second));
+        Error(member, as_eagerly_finalized, &info->GetField(field).second));
     seen_members_.insert(member);
   }
   return true;
 }
 
 bool CheckFinalizerVisitor::MightBeCollected(FieldPoint* point,
                                              bool* as_eagerly_finalized) {
   MightBeCollectedVisitor visitor(is_eagerly_finalized_);
   point->edge()->Accept(&visitor);
   *as_eagerly_finalized = visitor.as_eagerly_finalized();
   return visitor.might_be_collected();
 }