Blocking breakpoints

[awto]

In the current debugger implementation, the main thread is released on breakpoints. This way we can make other requests (such as some expressions evaluation, reloading sources etc).

However, it is a problem for not-transpiled or native code which calls the functions synchronously and requires everything is done before exiting the function (for example event.preventDefault called in the event handler).

We still can block the thread in these situations (in browser's main thread deprecated but still working sync XMLHttpRequest, and in node or WebWorker using Atomics.wait, or even resorting to the native debug API sometimes).