Ember Production Build is not using Protocol-relative URL for CDN

In my main.scss file, I have @import url(//fonts.googleapis.com/css?family=Roboto:400,500,700,900,300);

When I build the app for production, I see the url with http://

@font-face {
    font-family: Roboto;
    font-style: normal;
    font-weight: 300;
    src: local('Roboto Light'), local('Roboto-Light'),
        url(http://ift.tt/2pkij8Q)
        format('truetype')
}
@font-face {
    font-family: Roboto;
    font-style: normal;
    font-weight: 400;
    src: local('Roboto'), local('Roboto-Regular'),
        url(http://ift.tt/2qZWkjP)
        format('truetype')
}

Instead, I want it as url(//fonts.gstatic.com/s/roboto/v16/zN7GBFwfMP4uA6AR0HCoLQ.ttf), with the relative protocol-URL as //

Here is my package.json

"devDependencies": {
    "broccoli-asset-rev": "^2.4.5",
    "broccoli-funnel": "^1.0.1",
    "ember-ajax": "^2.4.1",
    "ember-cli": "2.11.0",
    "ember-cli-app-version": "^2.0.0",
    "ember-cli-babel": "^5.1.7",
    "ember-cli-bootstrap-datepicker": "0.5.5",
    "ember-cli-bootstrap-datetimepicker": "0.1.3",
    "ember-cli-content-security-policy": "0.5.0",
    "ember-cli-dependency-checker": "^1.3.0",
    "ember-cli-dropzonejs": "0.9.2",
    "ember-cli-focus-input": "^1.0.0",
    "ember-cli-htmlbars": "^1.1.1",
    "ember-cli-htmlbars-inline-precompile": "^0.3.3",
    "ember-cli-ic-ajax": "0.2.5",
    "ember-cli-inject-live-reload": "^1.4.1",
    "ember-cli-jshint": "^2.0.1",
    "ember-cli-moment-shim": "1.0.0",
    "ember-cli-qunit": "^3.0.1",
    "ember-cli-release": "0.2.9",
    "ember-cli-shims": "^1.0.2",
    "ember-cli-sri": "^2.1.0",
    "ember-cli-test-loader": "^1.1.0",
    "ember-cli-uglify": "^1.2.0",
    "ember-cli-underscore": "0.0.3",
    "ember-cli-version-checker": "^1.0.2",
    "ember-data": "2.11.0",
    "ember-disable-proxy-controllers": "^1.0.1",
    "ember-export-application-global": "^1.0.5",
    "ember-font-awesome": "3.0.1",
    "ember-inflector": "1.9.4",
    "ember-load-initializers": "^0.6.0",
    "ember-resolver": "^2.0.3",
    "ember-source": "^2.11.0",
    "ember-tag-search-input": "0.6.0",
    "ember-welcome-page": "^2.0.2",
    "eonasdan-bootstrap-datetimepicker-npm": "4.17.37",
    "jquery": "2.2.4",
    "loader.js": "^4.0.10",
    "moment": "2.11.2",
    "moment-timezone": "0.5.0"
  },
  "dependencies": {
    "ember-cli-sass": "^5.2.1"
  }