DevTools: [Persistence] validate persistence binding.

third_party/WebKit/LayoutTests/http/tests/inspector/persistence/persistence-test.js

 var initialize_PersistenceTest = function() {
 
 InspectorTest.preloadModule("persistence");
 InspectorTest.preloadModule("sources");
 
 Persistence.PersistenceBinding.prototype.toString = function()
 {
     var lines = [
         "{",
         "       network: " + this.network.url(),
@@ skipping 49 matching lines @@
         Workspace.workspace.removeEventListener(Workspace.Workspace.Events.UISourceCodeAdded, onUISourceCode);
         fulfill(uiSourceCode);
     }
 
     function filterCode(uiSourceCode)
     {
         return uiSourceCode.name() === name && uiSourceCode.project().type() === projectType;
     }
 }
 
+InspectorTest.fooJSContent = "\n\nwindow.foo = ()=>'foo';";
+
 InspectorTest.addFooJSFile = function(fs)
 {
-    return fs.root.mkdir("inspector").mkdir("persistence").mkdir("resources").addFile("foo.js", "\n\nwindow.foo = ()=>'foo';");
+    return fs.root.mkdir("inspector").mkdir("persistence").mkdir("resources").addFile("foo.js", InspectorTest.fooJSContent);
 }
 
 }