Fix to ensure the product mode builds again.

runtime/vm/timeline.h

 // 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 VM_TIMELINE_H_
 #define VM_TIMELINE_H_
 
 #include "include/dart_tools_api.h"
 
 #include "vm/allocation.h"
@@ skipping 369 matching lines @@
   TimelineDurationScope tds(thread,                                            \
                             Timeline::GetCompilerStream(),                     \
                             name);                                             \
   if (tds.enabled()) {                                                         \
     tds.SetNumArguments(1);                                                    \
     tds.CopyArgument(                                                          \
         0,                                                                     \
         "function",                                                            \
         function.ToLibNamePrefixedQualifiedCString());                         \
   }
+
+#define TIMELINE_FUNCTION_GC_DURATION(thread, name)                            \
+  TimelineDurationScope tds(thread, Timeline::GetGCStream(), name);
 #else
 #define TIMELINE_FUNCTION_COMPILATION_DURATION(thread, name, function)
+#define TIMELINE_FUNCTION_GC_DURATION(thread, name)
 #endif  // !PRODUCT
 
 // See |TimelineDurationScope| and |TimelineBeginEndScope|.
 class TimelineEventScope : public StackResource {
  public:
   bool enabled() const {
     return enabled_;
   }
 
   void SetNumArguments(intptr_t length);
@@ skipping 392 matching lines @@
 
  private:
   TimelineEventBlock* current_;
   TimelineEventRecorder* recorder_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_TIMELINE_H_