Replace more for loops in GN

tools/gn/function_write_file.cc

Index: tools/gn/function_write_file.cc
diff --git a/tools/gn/function_write_file.cc b/tools/gn/function_write_file.cc
index 69ae59ec877ab43f4a20f2a2abe9ee5771ad924a..55f4d5dc63a0e543fe9d58dfca7cbb2968188356 100644
--- a/tools/gn/function_write_file.cc
+++ b/tools/gn/function_write_file.cc
@@ -67,8 +67,8 @@ Value RunWriteFile(Scope* scope,
   std::ostringstream contents;
   if (args[1].type() == Value::LIST) {
     const std::vector<Value>& list = args[1].list_value();
-    for (size_t i = 0; i < list.size(); i++)
-      contents << list[i].ToString(false) << std::endl;
+    for (const auto& cur : list)
+      contents << cur.ToString(false) << std::endl;
   } else {
     contents << args[1].ToString(false);
   }