VM: Remove unused optimization of merging of sin/cos.

runtime/vm/flow_graph.h

 // Copyright (c) 2013, 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 RUNTIME_VM_FLOW_GRAPH_H_
 #define RUNTIME_VM_FLOW_GRAPH_H_
 
 #include "vm/bit_vector.h"
 #include "vm/growable_array.h"
 #include "vm/hash_map.h"
@@ skipping 333 matching lines @@
   void ComputeIsReceiverRecursive(PhiInstr* phi,
                                   GrowableArray<PhiInstr*>* unmark) const;
 
   void OptimizeLeftShiftBitAndSmiOp(
       ForwardInstructionIterator* current_iterator,
       Definition* bit_and_instr,
       Definition* left_instr,
       Definition* right_instr);
 
   void TryMergeTruncDivMod(GrowableArray<BinarySmiOpInstr*>* merge_candidates);
-  void TryMergeMathUnary(
-      GrowableArray<InvokeMathCFunctionInstr*>* merge_candidates);
 
   void AppendExtractNthOutputForMerged(Definition* instr,
                                        intptr_t ix,
                                        Representation rep,
                                        intptr_t cid);
 
   Thread* thread_;
 
   // DiscoverBlocks computes parent_ and assigned_vars_ which are then used
   // if/when computing SSA.
@@ skipping 169 matching lines @@
 
  private:
   GrowableArray<Definition*> defs_;
   BitVector* contains_vector_;
 };
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_FLOW_GRAPH_H_