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

src/compiler/js-intrinsic-lowering.cc

Index: src/compiler/js-intrinsic-lowering.cc
diff --git a/src/compiler/js-intrinsic-lowering.cc b/src/compiler/js-intrinsic-lowering.cc
index a3d27ee1a5b98a5e7e9d61c47b8a39682ad1be74..8879ebc8d92ff2a646da5550ee53af8988f61baf 100644
--- a/src/compiler/js-intrinsic-lowering.cc
+++ b/src/compiler/js-intrinsic-lowering.cc
@@ -42,6 +42,8 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
       return ReduceInlineDoubleHi(node);
     case Runtime::kInlineIsRegExp:
       return ReduceInlineIsInstanceType(node, JS_REGEXP_TYPE);
+    case Runtime::kInlineMathClz32:
+      return ReduceInlineMathClz32(node);
     case Runtime::kInlineMathFloor:
       return ReduceInlineMathFloor(node);
     case Runtime::kInlineMathSqrt:
@@ -179,6 +181,11 @@ Reduction JSIntrinsicLowering::ReduceInlineIsInstanceType(
 }
 
 
+Reduction JSIntrinsicLowering::ReduceInlineMathClz32(Node* node) {
+  return Change(node, machine()->Word32Clz());
+}
+
+
 Reduction JSIntrinsicLowering::ReduceInlineMathFloor(Node* node) {
   if (!machine()->HasFloat64RoundDown()) return NoChange();
   return Change(node, machine()->Float64RoundDown());