Remember thread's task when sampling use it when filtering

runtime/vm/source_report.cc

Index: runtime/vm/source_report.cc
diff --git a/runtime/vm/source_report.cc b/runtime/vm/source_report.cc
index 494ac53586ccd499bcbaa36055c36fa2cfb8eee4..1d3e818521487593de3d2a3e67e7f0fac3a30126 100644
--- a/runtime/vm/source_report.cc
+++ b/runtime/vm/source_report.cc
@@ -43,7 +43,9 @@ void SourceReport::Init(Thread* thread,
   next_script_index_ = 0;
   if (IsReportRequested(kProfile)) {
     // Build the profile.
-    SampleFilter samplesForIsolate(thread_->isolate(), -1, -1);
+    SampleFilter samplesForIsolate(thread_->isolate(),
+                                   Thread::kMutatorTask,
+                                   -1, -1);
     profile_.Build(thread, &samplesForIsolate, Profile::kNoTags);
   }
 }