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

runtime/vm/program_visitor.cc

Index: runtime/vm/program_visitor.cc
diff --git a/runtime/vm/program_visitor.cc b/runtime/vm/program_visitor.cc
index 256c9db84f5d8f233c5d0427f1b7b24000492a1a..14affdd5fa52d4d744e2fbacabf645c51475c55b 100644
--- a/runtime/vm/program_visitor.cc
+++ b/runtime/vm/program_visitor.cc
@@ -598,10 +598,10 @@ void ProgramVisitor::Dedup() {
   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