[builtins] Migrate Math.clz32 to a TurboFan builtin.

src/crankshaft/hydrogen.cc

Index: src/crankshaft/hydrogen.cc
diff --git a/src/crankshaft/hydrogen.cc b/src/crankshaft/hydrogen.cc
index 4e16f97cd170e007831e1658d442e18f94b6e242..d877e66330c4689175b91a1c3f9aa5eadd777263 100644
--- a/src/crankshaft/hydrogen.cc
+++ b/src/crankshaft/hydrogen.cc
@@ -12691,15 +12691,6 @@ void HOptimizedGraphBuilder::GenerateMathPow(CallRuntime* call) {
 }
 
 
-void HOptimizedGraphBuilder::GenerateMathClz32(CallRuntime* call) {
-  DCHECK(call->arguments()->length() == 1);
-  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
-  HValue* value = Pop();
-  HInstruction* result = NewUncasted<HUnaryMathOperation>(value, kMathClz32);
-  return ast_context()->ReturnInstruction(result, call->id());
-}
-
-
 void HOptimizedGraphBuilder::GenerateMathLogRT(CallRuntime* call) {
   DCHECK(call->arguments()->length() == 1);
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));