MenuItem.ts throw an error the Router injetored is null

Issue Type:
- [ ] Bug
- [ ] Feature
- [x] Help

Version & Environment:
package.json
``` json
{
"scripts": {
"ng": "ng",
"start": "ng serve",
"build": "ng build",
"test": "ng test",
"lint": "ng lint",
"e2e": "ng e2e"
},
"private": true,
"dependencies": {
"@angular/animations": "^6.0.3",
"@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/platform-browser": "^6.0.3",
"@angular/platform-browser-dynamic": "^6.0.3",
"@angular/router": "^6.0.3",
"core-js": "^2.5.4",
"element-angular": "^0.7.6",
"rxjs": "^6.0.0",
"zone.js": "^0.8.26"
},
"devDependencies": {
"@angular/compiler-cli": "^6.0.3",
"@angular-devkit/build-angular": "~0.6.6",
"typescript": "~2.7.2",
"@angular/cli": "~6.0.7",
"@angular/language-service": "^6.0.3",
"@types/jasmine": "~2.8.6",
"@types/jasminewd2": "~2.0.3",
"@types/node": "~8.9.4",
"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"
}
}

```
error in console:
Error: StaticInjectorError(AppModule)[ElMenuItem -> Router]:
StaticInjectorError(Platform: core)[ElMenuItem -> Router]:
NullInjectorError: No provider for Router!
at NullInjector.push../node_modules/@angular/core/fesm5/core.js.NullInjector.get (core.js:979)
at resolveToken (core.js:1232)
at tryResolveToken (core.js:1182)
at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:1077)
at resolveToken (core.js:1232)
at tryResolveToken (core.js:1182)
at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:1077)
at resolveNgModuleDep (core.js:9217)
at NgModuleRef_.push../node_modules/@angular/core/fesm5/core.js.NgModuleRef_.get (core.js:9911)
at resolveDep (core.js:10276)

Description:
I guess the problem is Angular6 that not has Router in RouterModule