Better solution to get all frame/iframes.

[qazbnm456]

In https://github.com/qazbnm456/lulumi-browser/commit/a92fafa1d95f64c5b2988b311d5bef46260d1c48, we use executeJavaScript to fetch frames. It works, but not good and security enough.

Someone has addressed this issue at https://github.com/electron/electron/issues/5115.