title: ES7 Object.entries() in TypeScript not working
body: <p>I have an issue with transpiling ES7 code with TypeScript. This code:</p>
  
  <pre><code>const sizeByColor = {
      red: 100,
      green: 500,
  };
  
  for ( const [ color, size ] of Object.entries(sizeByColor) ) {
      console.log(color);
      console.log(size);
  }
  </code></pre>
  
  <p>gives the error:</p>
  
  <p><code>TypeError: Object.entries is not a function</code></p>
  
  <p><strong>TypeScript v2.0.3</strong></p>
  
  <p>tsconfig.json:</p>
  
  <pre><code>{
  "compilerOptions": {
      "module": "commonjs",
      "target": "es6",
      "noImplicitAny": true,
      "noEmitOnError": true,
      "outDir": "dist",
      "allowSyntheticDefaultImports": true,
      "experimentalDecorators": true,
      "pretty": true,
      "lib": [ "es2017" ],
  },
  "exclude": [
      "node_modules"
  ],
  "include": [
      "./node_modules/@types/**/*.d.ts",
      "./src/**/*.ts"
  ]
  }
  </code></pre>
  
  <p>I want to iterate trough object with <code>Object.entries()</code>, so I assigned internal definitions <code>"lib": [ "es2017" ]</code>, but still, typescript wont allow me to transpile it.</p>