Assert MakeIterable is not called concurrently with mutator.

runtime/vm/pages.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/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 481 matching lines @@
   }
  private:
   const PageSpace* space_;
   MutexLocker ml_;
   NoGCScope no_gc;
   HeapPage* page_;
 };
 
 
 void PageSpace::MakeIterable() const {
-  // TODO(koda): Assert not called from concurrent sweeper task.
+  // Assert not called from concurrent sweeper task.
+  // TODO(koda): Use thread/task identity when implemented.
+  ASSERT(Isolate::Current()->heap() != NULL);
   if (bump_top_ < bump_end_) {
     FreeListElement::AsElement(bump_top_, bump_end_ - bump_top_);
   }
 }
 
 
 bool PageSpace::Contains(uword addr) const {
   for (ExclusivePageIterator it(this); !it.Done(); it.Advance()) {
     if (it.page()->Contains(addr)) {
       return true;
@@ skipping 602 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result = static_cast<int>((static_cast<double>(gc_time) /
                                    static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart