A string setTimeout/setInterval handler was compiled with new Function(fn) at
scheduling time. That diverged from the HTML spec in two ways: top-level
var/function declarations in the body stayed local to the compiled function
instead of becoming globals, and a syntax error was caught eagerly at
scheduling and turned into a silent no-op (that still returned a timer id)
rather than surfacing when the timer fires.
Defer string handlers to fire-time indirect eval ((0, eval)(src)), which runs
in the true global scope like a classic script, so declarations become global
and a SyntaxError is thrown when the timer elapses. Matches the dynamic-script
path, which already uses indirect eval for the same reason. Function handlers
are unchanged.
Fixes#558
Andrey Mnatsakanov
452cc8554f