Optimize functions containing try-catch.

runtime/vm/flow_graph_compiler.h

Index: runtime/vm/flow_graph_compiler.h
===================================================================
--- runtime/vm/flow_graph_compiler.h	(revision 22436)
+++ runtime/vm/flow_graph_compiler.h	(working copy)
@@ -241,6 +241,9 @@
   const GrowableArray<BlockEntryInstr*>& block_order() const {
     return block_order_;
   }
+
+  const FlowGraph& flow_graph() const { return flow_graph_; }
+
   DescriptorList* pc_descriptors_list() const {
     return pc_descriptors_list_;
   }
@@ -377,6 +380,9 @@
   // Fallthrough calls super equality.
   void EmitSuperEqualityCallPrologue(Register result, Label* skip_call);
 
+
+  void EmitTrySync(Instruction* instr, intptr_t try_index);
+
   intptr_t StackSize() const;
 
   // Returns assembler label associated with the given block entry.