Eslint-ignore generated DOM pinned properties dataset

This follows the example of the other generated files.
Avoids having to fight the presubmit check on regeneration.

Bug: 1325812
Change-Id: Ia925628fd5025a03b42aaf9e147e43ff752d2764
Signed-off-by: Victor Porof <victorporof@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3702268
Reviewed-by: Mathias Bynens <mathias@chromium.org>
diff --git a/scripts/webidl-properties/index.js b/scripts/webidl-properties/index.js
index ca78bc8..d8c6099 100644
--- a/scripts/webidl-properties/index.js
+++ b/scripts/webidl-properties/index.js
@@ -32,6 +32,8 @@
 const outPath = path.join(jsMetadataPath, 'DOMPinnedProperties.ts');
 const thisPath = path.relative(frontendPath, url.fileURLToPath(import.meta.url));
 
+const stringify = object => JSON.stringify(object, null, 2);
+
 fs.writeFileSync(outPath, `
 // Copyright 2022 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
@@ -41,7 +43,7 @@
 /**
  * All the specs used when generating the DOM pinned properties dataset.
  */
-export const SPECS = ${JSON.stringify(SPECS)};
+export const SPECS = ${stringify(SPECS)};
 
 export interface DOMPinnedWebIDLProp {
   // A flag specifying whether it's a "global" attribute.
@@ -81,5 +83,6 @@
  * This is an object with WebIDL type names as keys and their WebIDL properties
  * and inheritance/include chains as values.
  */
-export const DOMPinnedProperties: DOMPinnedPropertiesDataset = ${JSON.stringify(minimize(output))};
+export const DOMPinnedProperties: DOMPinnedPropertiesDataset = ${stringify(minimize(output))};
+
 `);