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

src/compiler/ia32/instruction-selector-ia32.cc

Index: src/compiler/ia32/instruction-selector-ia32.cc
diff --git a/src/compiler/ia32/instruction-selector-ia32.cc b/src/compiler/ia32/instruction-selector-ia32.cc
index 8ec091a0f6b4776bb981d727507320c4e47ac64d..ba21921dbb38c164f94df96c12074c93225fd7f2 100644
--- a/src/compiler/ia32/instruction-selector-ia32.cc
+++ b/src/compiler/ia32/instruction-selector-ia32.cc
@@ -503,6 +503,12 @@ void InstructionSelector::VisitWord32Ror(Node* node) {
 }
 
 
+void InstructionSelector::VisitWord32Clz(Node* node) {
+  IA32OperandGenerator g(this);
+  Emit(kIA32Lzcnt, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitInt32Add(Node* node) {
   IA32OperandGenerator g(this);