restore the normal pretest

package.json

@@ -25,7 +25,7 @@
     "eslint": "eslint \"{bin,example,src,test}/**/*.js\"",
     "tslint": "tslint \"{bin,example,src,test}/**/*.ts\" && tsc --noEmit",
     "shlint": "bash -n bin/*.sh && shellcheck bin/*.sh",
-    "pretest": "false && npm run clean && npm run lint && npm run build",
+    "pretest": "npm run clean && npm run lint && npm run build",
     "sloc": "sloc bin example src test index.ts --details --format cli-table --keys total,source,comment && sloc bin example src test index.ts",
     "test": "npm run test:chrome",
     "posttest": "npm run clean && npm run sloc",