message: build tooltip support preamble
diff: @@ -146,10 +146,11 @@ exports.travelSrcDir = function (srcDir, cb) {
  * @param {string} [opt]
  * @param {string} [opt.inputPath] Absolute input path.
  * @param {string} [opt.outputPath] Absolute output path.
  + * @param {string} [opt.preamble]
  * @param {Function} [opt.transform]
  * @param {Function} [opt.reserveDEV]
  */
  -exports.prePulishSrc = function ({inputPath, outputPath, transform, reserveDEV}) {
  +exports.prePulishSrc = function ({inputPath, outputPath, preamble, transform, reserveDEV}) {
  assert(inputPath && outputPath);
  console.log(
  @@ -173,6 +174,10 @@ exports.prePulishSrc = function ({inputPath, outputPath, transform, reserveDEV})
  code = transform({code, inputPath, outputPath});
  }
  + if (preamble) {
  + code = preamble + code;
  + }
  +
  fsExtra.ensureFileSync(outputPath);
  fs.writeFileSync(outputPath, code, {encoding:'utf-8'});
  };
  