[turbofan] Introduce separate SelectLowering reducer.

src/compiler/js-generic-lowering.cc

Index: src/compiler/js-generic-lowering.cc
diff --git a/src/compiler/js-generic-lowering.cc b/src/compiler/js-generic-lowering.cc
index 90d4d5efc89fe76e52f4fe994a67cc1c3a72a8e5..fb18ba198231343efa96ce751df667d834dc2bf1 100644
--- a/src/compiler/js-generic-lowering.cc
+++ b/src/compiler/js-generic-lowering.cc
@@ -65,7 +65,6 @@ Reduction JSGenericLowering::Reduce(Node* node) {
     Lower##x(node);     \
     break;
     DECLARE_CASE(Branch)
-    DECLARE_CASE(Select)
     JS_OP_LIST(DECLARE_CASE)
 #undef DECLARE_CASE
     default:
@@ -243,23 +242,6 @@ void JSGenericLowering::LowerBranch(Node* node) {
 }
 
 
-void JSGenericLowering::LowerSelect(Node* node) {
-  // TODO(bmeurer): This should probably be moved into a separate file.
-  SelectParameters const& p = SelectParametersOf(node->op());
-  Node* branch = graph()->NewNode(common()->Branch(p.hint()), node->InputAt(0),
-                                  graph()->start());
-  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
-  Node* vtrue = node->InputAt(1);
-  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
-  Node* vfalse = node->InputAt(2);
-  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
-  node->set_op(common()->Phi(p.type(), 2));
-  node->ReplaceInput(0, vtrue);
-  node->ReplaceInput(1, vfalse);
-  node->ReplaceInput(2, merge);
-}
-
-
 void JSGenericLowering::LowerJSUnaryNot(Node* node) {
   Callable callable = CodeFactory::ToBoolean(
       isolate(), ToBooleanStub::RESULT_AS_INVERSE_ODDBALL);