Implemented the ctz Turbo Fan operator for x64.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index 64f57026a9d7db81c2573791144b7d6331eb80b9..b72e60343542ba05eb13f6d6673c19af03238ae8 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -738,6 +738,8 @@ void InstructionSelector::VisitNode(Node* node) {
       return MarkAsWord64(node), VisitWord64Ror(node);
     case IrOpcode::kWord64Clz:
       return MarkAsWord64(node), VisitWord64Clz(node);
+    case IrOpcode::kWord64Ctz:
+      return MarkAsWord64(node), VisitWord64Ctz(node);
     case IrOpcode::kWord64Equal:
       return VisitWord64Equal(node);
     case IrOpcode::kInt32Add:
@@ -976,6 +978,9 @@ void InstructionSelector::VisitWord64Ror(Node* node) { UNIMPLEMENTED(); }
 void InstructionSelector::VisitWord64Clz(Node* node) { UNIMPLEMENTED(); }
 
 
+void InstructionSelector::VisitWord64Ctz(Node* node) { UNIMPLEMENTED(); }
+
+
 void InstructionSelector::VisitWord64Equal(Node* node) { UNIMPLEMENTED(); }