Background compilation fixes

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 248 matching lines @@
   if (!parse_class.IsNull()) {
     if (!parse_class.is_finalized() && !parse_class.is_marked_for_parsing()) {
       patch_list->Add(parse_class);
       parse_class.set_is_marked_for_parsing();
     }
   }
 }
 
 
 RawError* Compiler::CompileClass(const Class& cls) {
+  ASSERT(Thread::Current()->IsMutatorThread());
   // If class is a top level class it is already parsed.
   if (cls.IsTopLevel()) {
     return Error::null();
   }
   // If the class is already marked for parsing return immediately.
   if (cls.is_marked_for_parsing()) {
     return Error::null();
   }
   // If the class is a signature class there is no need to try and
   // compile it. Just finalize it directly.
@@ skipping 1547 matching lines @@
       task->set_compilation_result_queue(a);
       start_task = true;
     }
   }
   if (start_task) {
     Dart::thread_pool()->Run(isolate->background_compiler());
   }
 }
 
 }  // namespace dart