Enable concurrent optimization test after migrating scopes to Thread*

runtime/vm/compiler_stats.h

Index: runtime/vm/compiler_stats.h
diff --git a/runtime/vm/compiler_stats.h b/runtime/vm/compiler_stats.h
index a9ea0f14e8b97667c181cd8f646f04f5d3e654ec..8798c01762db7a41a3db9cdf73aaa794db63ad0f 100644
--- a/runtime/vm/compiler_stats.h
+++ b/runtime/vm/compiler_stats.h
@@ -67,10 +67,10 @@ class CompilerStats {
 #define INC_STAT(isolate, counter, incr)                                       \
   if (FLAG_compiler_stats) { (isolate)->compiler_stats()->counter += (incr); }
 
-#define CSTAT_TIMER_SCOPE(iso, t)                                              \
+#define CSTAT_TIMER_SCOPE(thr, t)                                              \
   TimerScope timer(FLAG_compiler_stats,                                        \
-  FLAG_compiler_stats ? &((iso)->compiler_stats()->t) : NULL,                  \
-  iso);
+      FLAG_compiler_stats ? &((thr)->isolate()->compiler_stats()->t) : NULL,   \
+      thr);
 
 }  // namespace dart