Fixed issue in MallocHooks where a MallocHookScope was accidentally removed during a merge, causing…

runtime/vm/source_report.cc

 // Copyright (c) 2015, 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.
 #ifndef PRODUCT
 #include "vm/source_report.h"
 
 #include "vm/compiler.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
@@ skipping 38 matching lines @@
                         const Script* script,
                         TokenPosition start_pos,
                         TokenPosition end_pos) {
   thread_ = thread;
   script_ = script;
   start_pos_ = start_pos;
   end_pos_ = end_pos;
   ClearScriptTable();
   if (IsReportRequested(kProfile)) {
     // Build the profile.
-    SampleFilter samplesForIsolate(thread_->isolate(), Thread::kMutatorTask, -1,
-                                   -1);
+    SampleFilter samplesForIsolate(thread_->isolate()->main_port(),
+                                   Thread::kMutatorTask, -1, -1);
     profile_.Build(thread, &samplesForIsolate, Profile::kNoTags);
   }
 }
 
 
 bool SourceReport::IsReportRequested(ReportKind report_kind) {
   return (report_set_ & report_kind) != 0;
 }
 
 
@@ skipping 456 matching lines @@
     VisitClosures(&ranges);
   }
 
   // Print the script table.
   JSONArray scripts(&report, "scripts");
   PrintScriptTable(&scripts);
 }
 
 }  // namespace dart
 #endif  // PRODUCT