Fix background compilation issues when creating snapshots.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, 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 "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "lib/stacktrace.h"
@@ skipping 1465 matching lines @@
   }
   if (isolate_snapshot_size == NULL) {
     RETURN_NULL_ERROR(isolate_snapshot_size);
   }
   // Finalize all classes if needed.
   Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   I->heap()->CollectAllGarbage();
+  I->StopBackgroundCompiler();
+
 #if defined(DEBUG)
   FunctionVisitor check_canonical(T);
   I->heap()->IterateObjects(&check_canonical);
 #endif  // #if defined(DEBUG).
 
   FullSnapshotWriter writer(vm_isolate_snapshot_buffer,
                             isolate_snapshot_buffer,
                             NULL, /* instructions_snapshot_buffer */
                             ApiReallocate,
                             false, /* snapshot_code */
@@ skipping 4615 matching lines @@
   return Api::Success();
 }
 #endif  // DART_PRECOMPILER
 
 
 DART_EXPORT bool Dart_IsRunningPrecompiledCode() {
   return Dart::IsRunningPrecompiledCode();
 }
 
 }  // namespace dart