Implemented the ctz Turbo Fan operator for x64.

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index 3cb823b164cc8218913fc049211437970bf49e69..169c8e988dcbc8e7c146b6b0e7e5adc829d694e7 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -936,6 +936,9 @@ void InstructionSelector::VisitWord32Clz(Node* node) {
 void InstructionSelector::VisitWord32Ctz(Node* node) { UNREACHABLE(); }
 
 
+void InstructionSelector::VisitWord64Ctz(Node* node) { UNREACHABLE(); }
+
+
 void InstructionSelector::VisitWord32Popcnt(Node* node) { UNREACHABLE(); }