{
  "name": "seed-element",
  "version": "0.0.0",
  "authors": [
    "Anonymous <anonymous@example.com>"
  ],
  "description": "Element providing solution to no problem in particular.",
  "keywords": [
    "web-component",
    "web-components",
    "polymer",
    "seed"
  ],
  "main": "seed-element.html",
  "license": "MIT",
  "homepage": "https://github.com/<USERNAME>/seed-element/",
  "ignore": [
    "/.*",
    "/tests/"
  ],
  "dependencies": {
    "polymer": "Polymer/polymer#^0.5.2"
  },
  "devDependencies": {
    "web-component-tester": "Polymer/web-component-tester#^2.0.5"
  }
}

{
  "name": "seed-element",
  "version": "0.0.0",
  "authors": [
    "Anonymous <anonymous@example.com>"
  ],
  "description": "Element providing solution to no problem in particular.",
  "keywords": [
    "web-component",
    "web-components",
    "polymer",
    "seed"
  ],
  "main": "seed-element.html",
  "license": "MIT",
  "homepage": "https://github.com/<USERNAME>/seed-element/",
  "ignore": [
    "/.*",
    "/tests/"
  ],
  "dependencies": {
    "polymer": "Polymer/polymer#^0.5.4"
  },
  "devDependencies": {
    "web-component-tester": "Polymer/web-component-tester#^2.2.3"
  }
}

Update to Polymer 0.5.4 and wct 2.2.3
Update to Polymer 0.5.4 and wct 2.2.3