Expose functionality to create a stack trace to internal vm code.

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
===================================================================
--- runtime/vm/flow_graph_builder.h	(revision 35317)
+++ runtime/vm/flow_graph_builder.h	(working copy)
@@ -143,14 +143,15 @@
   FlowGraphBuilder(ParsedFunction* parsed_function,
                    const Array& ic_data_array,
                    InlineExitCollector* exit_collector,
-                   intptr_t osr_id);
+                   intptr_t osr_id,
+                   bool is_optimizing);
 
   FlowGraph* BuildGraph();
 
   ParsedFunction* parsed_function() const { return parsed_function_; }
   const Array& ic_data_array() const { return ic_data_array_; }
 
-  void Bailout(const char* reason);
+  void Bailout(const char* reason) const;
 
   intptr_t AllocateBlockId() { return ++last_used_block_id_; }
   void SetInitialBlockId(intptr_t id) { last_used_block_id_ = id; }
@@ -184,6 +185,8 @@
   bool IsInlining() const { return (exit_collector_ != NULL); }
   InlineExitCollector* exit_collector() const { return exit_collector_; }
 
+  bool is_optimizing() const { return is_optimizing_; }
+
   ZoneGrowableArray<const Field*>* guarded_fields() const {
     return guarded_fields_;
   }
@@ -242,6 +245,10 @@
   // for OSR.
   const intptr_t osr_id_;
 
+  // The graph is being rebuilt for the optimizing compiler.
+  // Do not generate a different graph based on this flag.
+  const bool is_optimizing_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(FlowGraphBuilder);
 };