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

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index ac06da397a52751445addbca8144eeaaac2c60a7..f5f1264aa50500fbca5faf3bc9c7b906b329861f 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -555,6 +555,12 @@ void InstructionSelector::VisitWord64Ror(Node* node) {
 }
 
 
+void InstructionSelector::VisitWord32Clz(Node* node) {
+  X64OperandGenerator g(this);
+  Emit(kX64Lzcnt32, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitInt32Add(Node* node) {
   X64OperandGenerator g(this);