Implement logical AND/OR.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/object.h"
 #include "vm/os.h"
 #include "vm/scopes.h"
 
@@ skipping 112 matching lines @@
 
 void ReturnInstr::Postorder(GrowableArray<BlockEntryInstr*>* block_entries) {
   flip_mark();
 }
 
 
 void BranchInstr::Postorder(GrowableArray<BlockEntryInstr*>* block_entries) {
   flip_mark();
   // Visit the false successor before the true successor so they appear in
   // true/false order in reverse postorder.
+  ASSERT(false_successor_ != NULL);
+  ASSERT(true_successor_ != NULL);
   if (false_successor_->mark() != mark()) {
     false_successor_->Postorder(block_entries);
   }
   if (true_successor_->mark() != mark()) {
     true_successor_->Postorder(block_entries);
   }
 }
 
 
 }  // namespace dart