code: public final Object evaluateString(Scriptable scope, String source,
                                         String sourceName, int lineno,
                                         Object securityDomain)
      {
          Script script = compileString(source, sourceName, lineno,
                                        securityDomain);
          if (script != null) {
              return script.exec(this, scope);
          }
          return null;
      }
docs: Evaluate a JavaScript source string.
  
  The provided source name and line number are used for error messages
  and for producing debug information.
  
  @param scope the scope to execute in
  @param source the JavaScript source
  @param sourceName a string describing the source, such as a filename
  @param lineno the starting line number
  @param securityDomain an arbitrary object that specifies security
  information about the origin or owner of the script. For
  implementations that don't care about security, this value
  may be null.
  @return the result of evaluating the string
  @see org.mozilla.javascript.SecurityController