fix(@angular/cli): work around npm peerdep issue

NPM hoists dependencies with peerDeps of their own, leading to unmet peer dependencies.

This workaround should be safe for now since the only two packages that depend on `ajv-keywords@3.1.0` are `webpack` and `schema-utils`.

See #9691 (comment) and npm/npm#19877 for more information.

Fix #9691.

package.json

@@ -46,6 +46,7 @@
     "@angular-devkit/schematics": "0.3.1",
     "@schematics/angular": "0.3.1",
     "@schematics/package-update": "0.3.1",
+    "ajv": "^6.1.1",
     "autoprefixer": "^7.2.3",
     "cache-loader": "^1.2.0",
     "chalk": "~2.2.0",

packages/@angular/cli/lib/cli/index.ts

@@ -1,3 +1,10 @@
+// TODO: remove this commented AJV require.
+// We don't actually require AJV, but there is a bug with NPM and peer dependencies that is
+// whose workaround is to depend on AJV.
+// See https://github.com/angular/angular-cli/issues/9691#issuecomment-367322703 for details.
+// We need to add a require here to satisfy the dependency checker.
+// require('ajv');
+
 import * as path from 'path';
 
 const cli = require('../../ember-cli/lib/cli');

packages/@angular/cli/package.json

@@ -34,6 +34,7 @@
     "@ngtools/webpack": "1.10.0",
     "@schematics/angular": "0.3.1",
     "@schematics/package-update": "0.3.1",
+    "ajv": "^6.1.1",
     "autoprefixer": "^7.2.3",
     "cache-loader": "^1.2.0",
     "chalk": "~2.2.0",