[turbofan] Make context specialization into a reducer.

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 334 matching lines @@
     if (graph_builder.CreateGraph()) {
       data->set_context_node(graph_builder.GetFunctionContext());
     } else {
       data->set_compilation_failed();
     }
   }
 };
 
 
 struct ContextSpecializerPhase {
-  static const char* phase_name() { return nullptr; }
+  static const char* phase_name() { return "context specializing"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     SourcePositionTable::Scope pos(data->source_positions(),
                                    SourcePosition::Unknown());
     JSContextSpecializer spec(data->info(), data->jsgraph(),
                               data->context_node());
-    spec.SpecializeToContext();
+    GraphReducer graph_reducer(data->graph(), temp_zone);
+    graph_reducer.AddReducer(&spec);
+    graph_reducer.ReduceGraph();
   }
 };
 
 
 struct InliningPhase {
   static const char* phase_name() { return "inlining"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     SourcePositionTable::Scope pos(data->source_positions(),
                                    SourcePosition::Unknown());
@@ skipping 653 matching lines @@
 }
 
 
 void Pipeline::TearDown() {
   InstructionOperand::TearDownCaches();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8