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

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, 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/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 184 matching lines @@
         old_saved_ic_data.IsNull() ? 0 : old_saved_ic_data.Length();
     for (intptr_t i = 1; i < saved_len; i++) {
       ICData& ic_data = ICData::ZoneHandle(zone());
       ic_data ^= old_saved_ic_data.At(i);
       (*deopt_id_to_ic_data_)[ic_data.deopt_id()] = &ic_data;
     }
   }
   ASSERT(assembler != NULL);
   ASSERT(!list_class_.IsNull());
 
-  bool stack_traces_only = !FLAG_profiler;
+#if defined(PRODUCT)
+  const bool stack_traces_only = true;
+#else
+  const bool stack_traces_only = false;
+#endif
   code_source_map_builder_ = new (zone_)
       CodeSourceMapBuilder(stack_traces_only, caller_inline_id,
                            inline_id_to_token_pos, inline_id_to_function);
 }
 
 bool FlowGraphCompiler::IsUnboxedField(const Field& field) {
   bool valid_class =
       (SupportsUnboxedDoubles() && (field.guarded_cid() == kDoubleCid)) ||
       (SupportsUnboxedSimd128() && (field.guarded_cid() == kFloat32x4Cid)) ||
       (SupportsUnboxedSimd128() && (field.guarded_cid() == kFloat64x2Cid));
@@ skipping 1725 matching lines @@
   return true;
 }
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 }  // namespace dart