DevTools: trim the leading BOM char when parsing web manifest.

third_party/WebKit/Source/devtools/front_end/resources/AppManifestView.js

 // Copyright (c) 2016 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.
 /**
  * @implements {SDK.SDKModelObserver<!SDK.ResourceTreeModel>}
  * @unrestricted
  */
 Resources.AppManifestView = class extends UI.VBox {
   constructor() {
     super(true);
@@ skipping 88 matching lines @@
     this._errorsSection.clearContent();
     this._errorsSection.element.classList.toggle('hidden', !errors.length);
     for (var error of errors) {
       this._errorsSection.appendRow().appendChild(
           UI.createLabel(error.message, error.critical ? 'smallicon-error' : 'smallicon-warning'));
     }
 
     if (!data)
       return;
 
+    if (data.charCodeAt(0) === 0xFEFF)
+      data = data.slice(1);  // Trim the BOM as per https://tools.ietf.org/html/rfc7159#section-8.1.
+
     var parsedManifest = JSON.parse(data);
     this._nameField.textContent = stringProperty('name');
     this._shortNameField.textContent = stringProperty('short_name');
     this._startURLField.removeChildren();
     var startURL = stringProperty('start_url');
     if (startURL) {
       this._startURLField.appendChild(Components.Linkifier.linkifyURL(
           /** @type {string} */ (Common.ParsedURL.completeURL(url, startURL)), startURL));
     }
 
@@ skipping 35 matching lines @@
    * @param {!Common.Event} event
    */
   _addToHomescreen(event) {
     var target = SDK.targetManager.mainTarget();
     if (target && target.hasBrowserCapability()) {
       target.pageAgent().requestAppBanner();
       Common.console.show();
     }
   }
 };