Simplify scheduler API by removing zone scopes.

src/compiler/pipeline.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 478 matching lines @@
        << "Finished compiling method " << GetDebugName(info()).get()
        << " using Turbofan" << std::endl;
   }
 
   return code;
 }
 
 
 void Pipeline::ComputeSchedule(PipelineData* data) {
   PhaseScope phase_scope(data->pipeline_statistics(), "scheduling");
+  ZonePool::Scope zone_scope(data->zone_pool());
   Schedule* schedule =
-      Scheduler::ComputeSchedule(data->zone_pool(), data->graph());
+      Scheduler::ComputeSchedule(zone_scope.zone(), data->graph());
   TraceSchedule(schedule);
   if (VerifyGraphs()) ScheduleVerifier::Run(schedule);
   data->set_schedule(schedule);
 }
 
 
 Handle<Code> Pipeline::GenerateCodeForMachineGraph(Linkage* linkage,
                                                    Graph* graph,
                                                    Schedule* schedule) {
   ZonePool zone_pool(isolate());
@@ skipping 129 matching lines @@
 }
 
 
 void Pipeline::TearDown() {
   InstructionOperand::TearDownCaches();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8