[turbofan] Introduce separate SelectLowering reducer.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index 4dab244123d6aef4d34a4abeda1edafb63f71518..5c384c24c1fe81da1b18c6b67f11fa531ef74476 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -26,6 +26,7 @@
 #include "src/compiler/register-allocator.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/scheduler.h"
+#include "src/compiler/select-lowering.h"
 #include "src/compiler/simplified-lowering.h"
 #include "src/compiler/simplified-operator-reducer.h"
 #include "src/compiler/typer.h"
@@ -450,9 +451,11 @@ Handle<Code> Pipeline::GenerateCode() {
     PhaseScope phase_scope(pipeline_statistics.get(), "generic lowering");
     SourcePositionTable::Scope pos(data.source_positions(),
                                    SourcePosition::Unknown());
-    JSGenericLowering lowering(info(), data.jsgraph());
+    JSGenericLowering generic(info(), data.jsgraph());
+    SelectLowering select(data.jsgraph()->graph(), data.jsgraph()->common());
     GraphReducer graph_reducer(data.graph());
-    graph_reducer.AddReducer(&lowering);
+    graph_reducer.AddReducer(&generic);
+    graph_reducer.AddReducer(&select);
     graph_reducer.ReduceGraph();
 
     // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.