Address Siva's comments from https://codereview.chromium.org/1877973002/

runtime/vm/compiler_test.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 "platform/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/object.h"
@@ skipping 91 matching lines @@
 #endif
   BackgroundCompiler::EnsureInit(thread);
   Isolate* isolate = thread->isolate();
   ASSERT(isolate->background_compiler() != NULL);
   isolate->background_compiler()->CompileOptimized(func);
   Monitor* m = new Monitor();
   MonitorLocker ml(m);
   while (!func.HasOptimizedCode()) {
     ml.WaitWithSafepointCheck(thread, 1);
   }
-  BackgroundCompiler::Stop(isolate->background_compiler());
+  BackgroundCompiler::Stop(isolate);
 }
 
 
 TEST_CASE(RegenerateAllocStubs) {
   const char* kScriptChars =
             "class A {\n"
             "}\n"
             "unOpt() => new A(); \n"
             "optIt() => new A(); \n"
             "A main() {\n"
@@ skipping 100 matching lines @@
   EXPECT(val.IsInteger());
   EXPECT_EQ(7, Integer::Cast(val).AsInt64Value());
 
   intptr_t final_class_table_size =
       Isolate::Current()->class_table()->NumCids();
   // Eval should not eat into this non-renewable resource.
   EXPECT_EQ(initial_class_table_size, final_class_table_size);
 }
 
 }  // namespace dart