Replace more for loops in GN

tools/gn/function_foreach.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 
 namespace functions {
@@ skipping 83 matching lines @@
     return Value();
   }
 
   // If the loop variable was previously defined in this scope, save it so we
   // can put it back after the loop is done.
   const Value* old_loop_value_ptr = scope->GetValue(loop_var);
   Value old_loop_value;
   if (old_loop_value_ptr)
     old_loop_value = *old_loop_value_ptr;
 
-  for (size_t i = 0; i < list.size(); i++) {
-    scope->SetValue(loop_var, list[i], function);
+  for (const auto& cur : list) {
+    scope->SetValue(loop_var, cur, function);
     block->ExecuteBlockInScope(scope, err);
     if (err->has_error())
       return Value();
   }
 
   // Put back loop var.
   if (old_loop_value_ptr) {
     // Put back old value. Use the copy we made, rather than use the pointer,
     // which will probably point to the new value now in the scope.
     scope->SetValue(loop_var, old_loop_value, old_loop_value.origin());
   } else {
     // Loop variable was undefined before loop, delete it.
     scope->RemoveIdentifier(loop_var);
   }
 
   return Value();
 }
 
 }  // namespace functions