Fix bug in ninja generator when there's no default action.

test/rules/src/subdir2/no_action.gyp

+# Copyright (c) 2012 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Test that the case where an action is only specified under a conditional is
+# evaluated appropriately.
+{
+  'targets': [
+    {
+      'target_name': 'extension_does_not_match_sources_and_no_action',
+      'type': 'none',
+      'msvs_cygwin_shell': 0,
+      'sources': [
+        'file1.in',
+        'file2.in',
+      ],
+      'rules': [
+        {
+          'rule_name': 'assemble',
+          'extension': 'asm',
+          'outputs': [
+            '<(RULE_INPUT_ROOT).fail',
+          ],
+          'conditions': [
+            # Always fails.
+            [ '"true"=="false"', {
+              'action': [
+                'python', '../copy-file.py', '<(RULE_INPUT_PATH)', '<@(_outputs)',
+              ],
+              'process_outputs_as_sources': 1,
+              'message': 'test_rule',
+            }],
+          ],
+        },
+      ],
+    },
+  ],
+}