Reapply "[vm] Don't enable the profiler by default. Enable the profiler at startup with --observe, …

runtime/vm/program_visitor.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.
 
 #include "vm/program_visitor.h"
 
 #include "vm/deopt_instructions.h"
 #include "vm/hash_map.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
@@ skipping 580 matching lines @@
 
   // TODO(rmacnak): Bind static calls whose target has been compiled. Forward
   // references to disabled code.
   ShareMegamorphicBuckets();
   DedupStackMaps();
   DedupPcDescriptors();
   NOT_IN_PRECOMPILED(DedupDeoptEntries());
   DedupCodeSourceMaps();
   DedupLists();
 
-  if (!FLAG_profiler) {
-    // Reduces binary size but obfuscates profiler results.
-    DedupInstructions();
-  }
+#if defined(PRODUCT)
+  // Reduces binary size but obfuscates profiler results.
+  DedupInstructions();
+#endif
 }
 
 }  // namespace dart