title: Cannot find name 'TextDecoder' in TypeScript.2.7
body: <p>I am creating an Angular 6 application (using TypeScript 2.7) and want to use the TextDecoder native function.  When I run ng build --aot I receive the error: error TS2304: Cannot find name 'TextDecoder'.</p>
  
  <p>Any help would be appreciated.  Below is my tsconfig.json file and the list of packages from my package.json file.</p>
  
  <p>Thanks,
  Bob</p>
  
  <pre><code>{
    "compileOnSave": false,
    "compilerOptions": {
      "baseUrl": "./",
      "outDir": "./dist/out-tsc",
      "sourceMap": true,
      "declaration": false,
      "moduleResolution": "node",
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true,
      "target": "es5",
      "typeRoots": [
        "node_modules/@types"
      ],
      "lib": [
        "es2017",
        "dom"
      ]
    }
  }
  </code></pre>
  
  <hr>
  
  <pre><code>  "dependencies": {
      "@angular/animations": "^6.0.5",
      "@angular/cdk": "^6.2.1",
      "@angular/common": "^6.0.3",
      "@angular/compiler": "^6.0.3",
      "@angular/core": "^6.0.3",
      "@angular/forms": "^6.0.3",
      "@angular/http": "^6.0.3",
      "@angular/material": "^6.2.1",
      "@angular/platform-browser": "^6.0.3",
      "@angular/platform-browser-dynamic": "^6.0.3",
      "@angular/router": "^6.0.3",
      "bootstrap": "^4.1.1",
      "core-js": "^2.5.4",
      "hammerjs": "^2.0.8",
      "npm": "^6.1.0",
      "rxjs": "^6.0.0",
      "zone.js": "^0.8.26"
    },
    "devDependencies": {
      "@angular-devkit/build-angular": "~0.6.8",
      "@angular/cli": "~6.0.8",
      "@angular/compiler-cli": "^6.0.3",
      "@angular/language-service": "^6.0.3",
      "@types/jasmine": "~2.8.6",
      "@types/jasminewd2": "~2.0.3",
      "@types/node": "^10.5.7",
      "codelyzer": "~4.2.1",
      "jasmine-core": "~2.99.1",
      "jasmine-spec-reporter": "~4.2.1",
      "karma": "~1.7.1",
      "karma-chrome-launcher": "~2.2.0",
      "karma-coverage-istanbul-reporter": "~2.0.0",
      "karma-jasmine": "~1.1.1",
      "karma-jasmine-html-reporter": "^0.2.2",
      "protractor": "~5.3.0",
      "ts-node": "~5.0.1",
      "tslint": "~5.9.1",
      "typescript": "~2.7.2"
    }
  }
  </code></pre>