Don't wait to close tabs waiting for JavaScript dialogs.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 7cb552bb0560ff31b2017a15d23a51fa9ea36289..e9f93fc948ff68f1ff9ba6bc7e7d5fae44539e5f 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -4138,6 +4138,7 @@ void WebContentsImpl::RunJavaScriptMessage(
       !delegate_->GetJavaScriptDialogManager(this);
 
   if (!suppress_this_message) {
+    is_showing_javascript_dialog_ = true;
     dialog_manager_ = delegate_->GetJavaScriptDialogManager(this);
     dialog_manager_->RunJavaScriptDialog(
         this, frame_url, javascript_message_type, message, default_prompt,
@@ -4188,6 +4189,10 @@ void WebContentsImpl::RunBeforeUnloadConfirm(
                  false));
 }
 
+bool WebContentsImpl::IsJavaScriptDialogShowing() const {
+  return is_showing_javascript_dialog_;
+}
+
 void WebContentsImpl::RunFileChooser(RenderFrameHost* render_frame_host,
                                      const FileChooserParams& params) {
   if (delegate_)
@@ -5063,6 +5068,7 @@ void WebContentsImpl::OnDialogClosed(int render_process_id,
                       BeforeUnloadDialogCancelled());
   }
 
+  is_showing_javascript_dialog_ = false;
   is_showing_before_unload_dialog_ = false;
   if (rfh) {
     rfh->JavaScriptDialogClosed(reply_msg, success, user_input,