We don't want to carry over exceptions across multiple
Document::run_javascript() calls as Interpreter::run() and every of its
exception checks will get confused - in this case there would be an
exception, but not because a certain action failed.
Real-life example:
<script>var a = {}; a.test()</script>
<script>alert("It worked!")</script>
The above HTML will invoke Document::run_javascript() twice, the first
call will result in a TypeError, which is still stored during the second
call. The interpreter will eventually call the following functions (in
order) for the alert() invocation:
- Identifier::execute()
- Interpreter::get_variable()
- Object::get() (on the global object)
That last Object::get() call has an exception check which is triggered
as we still carry around the exception from earlier - and eventually
returns an empty value.
Long story short, the second script will wrongly fail with
"ReferenceError, 'alert' is not defined".
Fixes#3091.
1d728af5c4