Revert "Revert "Introduce Goto instructions to the flow graph.""

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
diff --git a/runtime/vm/flow_graph_builder.h b/runtime/vm/flow_graph_builder.h
index fe4585dfd368cf1b2b6b4347943a3f36adb00189..f2d95a653e477a1a0d58d22112539bcae4bf33c6 100644
--- a/runtime/vm/flow_graph_builder.h
+++ b/runtime/vm/flow_graph_builder.h
@@ -122,9 +122,12 @@ class EffectGraphVisitor : public AstNodeVisitor {
   UseVal* Bind(Computation* computation);
   // Append a computation with no uses.  Assumes this graph is open.
   void Do(Computation* computation);
-  // Append a single (non-Bind, non-Do) instruction.  Assumes this graph is
-  // open.
+  // Append a single (non-Definition, non-Entry) instruction.  Assumes this
+  // graph is open.
   void AddInstruction(Instruction* instruction);
+  // Append a Goto (unconditional control flow) instruction and close
+  // the graph fragment.  Assumes this graph fragment is open.
+  void Goto(JoinEntryInstr* join);
 
   // Append a 'diamond' branch and join to this graph, depending on which
   // parts are reachable.  Assumes this graph is open.