Fix help and error messages.

tools/gn/function_template.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/functions.h"
 
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/value.h"
 
@@ skipping 48 matching lines @@
     "\n"
     "    # Intermediate target to compile IDL to C source.\n"
     "    custom(\"${target_name}_code_gen\") {\n"
     "      # The |sources| will be inherited from the surrounding scope so\n"
     "      # we don't need to redefine it.\n"
     "      script = \"foo.py\"\n"
     "      outputs = filter  # Variable from above.\n"
     "    }\n"
     "\n"
     "    # Name the static library the same as the template invocation so\n"
-    "    # instanting this template produces something that other targets\n"
+    "    # instancing this template produces something that other targets\n"
     "    # can link to in their deps.\n"
     "    static_library(target_name) {\n"
     "      # Generates the list of sources.\n"
     "      # See \"gn help process_file_template\"\n"
     "      sources = process_file_template(sources, filter)\n"
     "    }\n"
     "  }\n"
     "\n"
     "Example of invoking the resulting template:\n"
     "\n"
@@ skipping 24 matching lines @@
     err->AppendSubErr(Err(existing_template->function(),
                           "Previous definition."));
     return Value();
   }
 
   scope->AddTemplate(template_name, function);
   return Value();
 }
 
 }  // namespace functions