If a rethrow is encountered in the catch block, then its handler must be marked that it needs stack…

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
===================================================================
--- runtime/vm/flow_graph_builder.h	(revision 26962)
+++ runtime/vm/flow_graph_builder.h	(working copy)
@@ -128,6 +128,10 @@
   void set_try_index(intptr_t value) { try_index_ = value; }
   intptr_t try_index() const { return try_index_; }
 
+  // Manage the currently active catch-handler try index.
+  void set_catch_try_index(intptr_t value) { catch_try_index_ = value; }
+  intptr_t catch_try_index() const { return catch_try_index_; }
+
   void AddCatchEntry(CatchBlockEntryInstr* entry);
 
   intptr_t num_copied_params() const {
@@ -169,6 +173,7 @@
   intptr_t last_used_block_id_;
   intptr_t context_level_;
   intptr_t try_index_;
+  intptr_t catch_try_index_;
   intptr_t loop_depth_;
   GraphEntryInstr* graph_entry_;