Make javascript dialogs into top-level windows.

chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc

Index: chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
diff --git a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
index 016ffe5e0d072b0a256e317d0faa31696c7f2a53..2cfeaed32bfaeca3f862bc0b3d83ebc63ae9dc9a 100644
--- a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
+++ b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
@@ -84,12 +84,9 @@ JavaScriptAppModalDialog::~JavaScriptAppModalDialog() {
 NativeAppModalDialog* JavaScriptAppModalDialog::CreateNativeDialog() {
   gfx::NativeWindow parent_window =
       web_contents()->GetView()->GetTopLevelNativeWindow();
-#if defined(USE_AURA)
-  if (!parent_window->GetRootWindow()) {
-    // When we are part of a WebContents that isn't actually being displayed on
-    // the screen, we can't actually attach to it.
-    parent_window = NULL;
-  }
+#if defined(USE_AURA) && defined(OS_WIN)
+  // Javascript dialogs should be top-level windows in desktop WinAura.
+  parent_window = NULL;
 #endif
   return NativeAppModalDialog::CreateNativeJavaScriptPrompt(this,
                                                             parent_window);