DevTools: Fix "Run Snippet" button not showing when viewing a snippet right after opening DevTools

third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 63 matching lines @@
     navigatorMenuButton.setTitle(WebInspector.UIString("More options"));
     navigatorToolbar.appendToolbarItem(navigatorMenuButton);
     tabbedPane.appendAfterTabStrip(navigatorToolbar.element);
     this.editorView.setSidebarWidget(tabbedPane);
 
     this._sourcesView = new WebInspector.SourcesView();
     this._sourcesView.addEventListener(WebInspector.SourcesView.Events.EditorSelected, this._editorSelected.bind(this));
     this._sourcesView.addEventListener(WebInspector.SourcesView.Events.EditorClosed, this._editorClosed.bind(this));
     this._sourcesView.registerShortcuts(this.registerShortcuts.bind(this));
     this.editorView.setMainWidget(this._sourcesView);
+    this._editorChanged(this._sourcesView.currentUISourceCode());
 
     this.sidebarPanes = {};
     this.sidebarPanes.threads = null;
     this.sidebarPanes.watchExpressions = new WebInspector.WatchExpressionsSidebarPane();
     this.sidebarPanes.callstack = new WebInspector.CallStackSidebarPane();
     this.sidebarPanes.callstack.addEventListener(WebInspector.CallStackSidebarPane.Events.CallFrameSelected, this._callFrameSelectedInSidebar.bind(this));
     this.sidebarPanes.callstack.registerShortcuts(this.registerShortcuts.bind(this));
 
     this.sidebarPanes.scopechain = new WebInspector.ScopeChainSidebarPane();
     this.sidebarPanes.jsBreakpoints = new WebInspector.JavaScriptBreakpointsSidebarPane(WebInspector.breakpointManager, this.showUISourceCode.bind(this));
@@ skipping 1372 matching lines @@
     __proto__: WebInspector.VBox.prototype
 }
 
 /**
  * @return {boolean}
  */
 WebInspector.SourcesPanel.WrapperView.isShowing = function()
 {
     return !!WebInspector.SourcesPanel.WrapperView._instance && WebInspector.SourcesPanel.WrapperView._instance.isShowing();
 }