Install child folder deps through helper script (#500)

_install_deps.js

@@ -0,0 +1,43 @@
+/**
+ * @license
+ * Copyright 2016 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const exec = require('child_process').exec;
+
+const cwd = require('path').resolve();
+const corePath = `${cwd}/lighthouse-core`;
+const extPath = `${cwd}/lighthouse-extension`;
+
+const npm = 'npm --prefix';
+const cmd = `${npm} ${corePath} install ${corePath} && ${npm} ${extPath} install ${extPath}`;
+
+// Tell the user what command we're about to execute
+console.log(cmd);
+console.log('...');
+
+exec(cmd,
+  function(error, stdout, stderr) {
+    process.stderr.write(stderr);
+    process.stdout.write(stdout);
+    if (stdout.length === 0) {
+      console.log('The full install may not have completed.');
+      console.log('To manually install child dependencies:');
+      console.log(`    ${cmd}`);
+    }
+  });
+

package.json

@@ -9,9 +9,7 @@
   },
   "scripts": {
     "//": "// passing through tasks to core",
-    "postinstall": "npm run core-install && npm run extension-install",
-    "core-install": "npm --prefix ./lighthouse-core install ./lighthouse-core",
-    "extension-install": "npm --prefix ./lighthouse-extension install ./lighthouse-extension",
+    "postinstall": "node _install_deps.js",
     "lint": "eslint .",
     "smoke": "lighthouse-cli/scripts/run-smoke-tests.sh",
     "coverage": "istanbul cover -x \"**/third_party/**\" _mocha -- $(find */test -name '*.js') --timeout 60000",