Add flow graph printing into a .cfg file with flag --print-flow-graph-file.

vm/isolate.h

 // Copyright (c) 2012, 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_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/class_table.h"
@@ skipping 172 matching lines @@
   static Dart_IsolateInterruptCallback InterruptCallback();
 
   GcPrologueCallbacks& gc_prologue_callbacks() {
     return gc_prologue_callbacks_;
   }
 
   GcEpilogueCallbacks& gc_epilogue_callbacks() {
     return gc_epilogue_callbacks_;
   }
 
+  FILE* flow_graph_file() {
+    return flow_graph_file_;
+  }
+
+  void set_flow_graph_file(FILE* file) {
+    flow_graph_file_ = file;
+  }
+
  private:
   Isolate();
 
   void BuildName(const char* name_prefix);
   void PrintInvokedFunctions();
 
   static uword GetSpecifiedStackSize();
 
   static const uword kStackSizeBuffer = (128 * KB);
   static const uword kDefaultStackSize = (1 * MB);
@@ skipping 19 matching lines @@
   intptr_t ast_node_id_;  // Deprecate.
   intptr_t computation_id_;
   RawArray* ic_data_array_;
   Mutex* mutex_;  // protects stack_limit_ and saved_stack_limit_.
   uword stack_limit_;
   uword saved_stack_limit_;
   MessageHandler* message_handler_;
   uword spawn_data_;
   GcPrologueCallbacks gc_prologue_callbacks_;
   GcEpilogueCallbacks gc_epilogue_callbacks_;
+  FILE* flow_graph_file_;
 
   static Dart_IsolateCreateCallback create_callback_;
   static Dart_IsolateInterruptCallback interrupt_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };
 
 // When we need to execute code in an isolate, we use the
 // StartIsolateScope.
 class StartIsolateScope {
@@ skipping 54 matching lines @@
   Isolate* new_isolate_;
   Isolate* saved_isolate_;
   uword saved_stack_limit_;
 
   DISALLOW_COPY_AND_ASSIGN(SwitchIsolateScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_