[turbofan] Turn Math.clz32 into an inlinable builtin.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 5153897fbf8148068e287d023eb7cb3ecd8c880e..6f349b79c4a1eac2e3b9ec332f49d63bd93071e7 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -12030,6 +12030,15 @@ 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::GenerateMathFloor(CallRuntime* call) {
   DCHECK(call->arguments()->length() == 1);
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));