Windows: Avoid assertion when entering zero-length text in the default JavaScript prompt dialog (issue #862).

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@1045 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

libcef/browser/javascript_dialog_win.cc

@@ -61,9 +61,11 @@ INT_PTR CALLBACK CefJavaScriptDialog::DialogProc(HWND dialog,
           if (owner->message_type_ == content::JAVASCRIPT_MESSAGE_TYPE_PROMPT) {
             size_t length =
                 GetWindowTextLength(GetDlgItem(dialog, IDC_PROMPTEDIT)) + 1;
+            if (length > 1) {
               GetDlgItemText(dialog, IDC_PROMPTEDIT,
                              WriteInto(&user_input, length), length);
             }
+          }
           break;
         case IDCANCEL:
           finish = true;