Fix bug with captured parameters and optimized try-catch.

runtime/vm/flow_graph.h

Index: runtime/vm/flow_graph.h
===================================================================
--- runtime/vm/flow_graph.h	(revision 41095)
+++ runtime/vm/flow_graph.h	(working copy)
@@ -263,6 +263,10 @@
     return deferred_prefixes_;
   }
 
+  BitVector* captured_parameters() const {
+    return captured_parameters_;
+  }
+
  private:
   friend class IfConverter;
   friend class BranchSimplifier;
@@ -338,6 +342,7 @@
   ZoneGrowableArray<const Field*>* guarded_fields_;
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes_;
   DirectChainedHashMap<ConstantPoolTrait> constant_instr_pool_;
+  BitVector* captured_parameters_;
 };