Refactor to support multiple outputs in location summary

runtime/vm/flow_graph_compiler_x64.cc

 // 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 697 matching lines @@
   __ popq(RCX);  // Remove pushed instantiator.
 }
 
 
 void FlowGraphCompiler::EmitInstructionEpilogue(Instruction* instr) {
   if (is_optimizing()) {
     return;
   }
   Definition* defn = instr->AsDefinition();
   if ((defn != NULL) && defn->is_used()) {
-    Location value = defn->locs()->out();
+    Location value = defn->locs()->out(0);
     if (value.IsRegister()) {
       __ pushq(value.reg());
     } else {
       ASSERT(value.IsStackSlot());
       __ pushq(value.ToStackSlotAddress());
     }
   }
 }
 
 
@@ skipping 1109 matching lines @@
   __ movups(reg, Address(RSP, 0));
   __ AddImmediate(RSP, Immediate(kFpuRegisterSize), PP);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64