Build Vega bundles separately from other code

This fixes jupyterlab#6709, and is a follow up to jupyterlab#6572. It separates building
vega assets from the rest of our package management. That way, we can
avoid any hoisting issues that we were seeing (possibly from yarnpkg/yarn#5520).

To test this, you can try this notebook which should render
both versions without errors:

https://gist.github.com/saulshanabrook/97c28550ab12e684adc3c325038537ce

package.json

@@ -15,14 +15,6 @@
       "tests/test-*",
       "testutils",
       "jupyterlab/tests/mock_packages/extension"
-    ],
-    "nohoist": [
-      "**/vega-embed",
-      "**/vega-lite",
-      "**/vega",
-      "**/vega-embed/**",
-      "**/vega-lite/**",
-      "**/vega/**"
     ]
   },
   "scripts": {
@@ -40,7 +32,9 @@
     "build:test": "lerna run build --scope \"@jupyterlab/test-*\" --concurrency 1",
     "build:testutils": "cd testutils && jlpm run build",
     "build:utils": "cd buildutils && jlpm run build",
-    "build:vega": "lerna run build:webpack --scope \"@jupyterlab/vega*-extension\" --concurrency 1",
+    "build:vega": "jlpm run build:vega:4 && jlpm run build:vega:5",
+    "build:vega:4": "cd prebuild/vega4 && jlpm && jlpm run build",
+    "build:vega:5": "cd prebuild/vega5 && jlpm && jlpm run build",
     "bump:js:major": "node buildutils/lib/bump-js-major.js",
     "bumpversion": "node buildutils/lib/bumpversion.js",
     "clean": "jlpm run clean:dev && jlpm run clean:packages",

packages/vega4-extension/package.json

@@ -27,8 +27,7 @@
     "lib": "lib/"
   },
   "scripts": {
-    "build": "tsc -b && webpack",
-    "build:webpack": "webpack",
+    "build": "tsc -b",
     "clean": "rimraf lib",
     "docs": "typedoc --options tdoptions.json --theme ../../typedoc-theme src",
     "prepublishOnly": "npm run build",
@@ -44,10 +43,7 @@
     "rimraf": "~2.6.2",
     "typedoc": "^0.14.2",
     "typescript": "~3.5.1",
-    "vega": "^4.4.0",
-    "vega-embed": "^4.2.0",
-    "vega-lite": "^2.7.0",
-    "webpack": "^4.32.2"
+    "vega-embed": "^4.2.0"
   },
   "publishConfig": {
     "access": "public"

packages/vega5-extension/package.json

@@ -27,8 +27,7 @@
     "lib": "lib/"
   },
   "scripts": {
-    "build": "tsc -b && webpack",
-    "build:webpack": "webpack",
+    "build": "tsc -b",
     "clean": "rimraf lib",
     "docs": "typedoc --options tdoptions.json --theme ../../typedoc-theme src",
     "prepublishOnly": "npm run build",
@@ -44,10 +43,7 @@
     "rimraf": "~2.6.2",
     "typedoc": "^0.14.2",
     "typescript": "~3.5.1",
-    "vega": "^5.4.0",
-    "vega-embed": "^4.2.0",
-    "vega-lite": "^3.3.0",
-    "webpack": "^4.32.2"
+    "vega-embed": "^4.2.0"
   },
   "publishConfig": {
     "access": "public"

prebuild/vega4/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "",
+  "version": "",
+  "scripts": {
+    "build": "webpack"
+  },
+  "devDependencies": {
+    "vega": "^4.4.0",
+    "vega-embed": "^4.2.0",
+    "vega-lite": "^2.7.0",
+    "webpack": "^4.32.2"
+  },
+  "publishConfig": {
+    "access": "private"
+  }
+}

prebuild/vega4/webpack.config.js

@@ -0,0 +1,19 @@
+var path = require('path');
+
+module.exports = {
+  entry: 'vega-embed',
+  mode: 'production',
+  devtool: 'source-map',
+  output: {
+    path: path.resolve(
+      __dirname,
+      '..',
+      '..',
+      'packages',
+      'vega4-extension',
+      'lib'
+    ),
+    filename: 'built-vega-embed.js',
+    libraryTarget: 'commonjs2'
+  }
+};