function statement(toks, i, n, handler) {
    if (i < n) {
      var tok = toks[i];
      if (tok.charAt(0) === '@') {
        return atrule(toks, i, n, handler, true);
      } else {
        return ruleset(toks, i, n, handler);
      }
    } else {
      return i;
    }
  }
parseCssDeclarations parses a run of declaration productions as seen in the
body of the HTML5 {@code style} attribute.

@param {string} cssText CSS3 content to parse as a run of declarations.
@param {Object} handler An object like <pre>{
  declaration: function (property, valueArray) { ... },
}</pre>