[global] Remaps self.Common.settings

This CL changes references to self.Common.settings (the global
instance of SDK.Common.Settings) over to
Common.Settings.Settings.instance(). To keep both TypeScript and
Closure happy we must make a method on the Settings class itself,
since it only allows private constructors to be accessed by static
methods on the class.

Bug: 1058320
Change-Id: I04afc8caf64acf29cdda13ef03ad05cfff4786a1
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2091450
Commit-Queue: Paul Lewis <[email protected]>
Reviewed-by: Tim van der Lippe <[email protected]>
diff --git a/front_end/resources/ResourcesPanel.js b/front_end/resources/ResourcesPanel.js
index 116512c..0a073cf 100644
--- a/front_end/resources/ResourcesPanel.js
+++ b/front_end/resources/ResourcesPanel.js
@@ -20,7 +20,8 @@
     super('resources');
     this.registerRequiredCSS('resources/resourcesPanel.css');
 
-    this._resourcesLastSelectedItemSetting = self.Common.settings.createSetting('resourcesLastSelectedElementPath', []);
+    this._resourcesLastSelectedItemSetting =
+        Common.Settings.Settings.instance().createSetting('resourcesLastSelectedElementPath', []);
 
     /** @type {?UI.Widget.Widget} */
     this.visibleView = null;