function jsExec(stmt) {
  try {
    eval(stmt);
    return true;
  } catch (e) {
    return false;
  }
}
Wrapper for the eval() builtin function to execute statements. This
guards against exceptions thrown, but doesn't return a
value. Still, mostly for testability, it returns a boolean to
indicate whether execution was successful. NOTE:
javascript's eval semantics is murky in that it confounds
expression evaluation and statement execution into a single
construct. Cf. jsEval().

@param {String} stmt
@return {Boolean}