Initial attempt at fixing sinonjs#1805

See sinonjs#1805

Not functional bundle. Gets this error:

$ node -r esm -e 'import sinon from ./bundle-esm'
file:///home/carlerik/dev/sinon/bundle-esm.js:1
import typeDetect from 'type-detect';

SyntaxError: Missing export 'default' in ES module: file:///home/carlerik/dev/sinon/node_modules/diff/lib/index.js
    at Object.<anonymous> (file:///home/carlerik/dev/sinon/bundle-esm.js:1)

package.json

@@ -24,6 +24,7 @@
     "test": "run-s test-node test-headless test-webworker test-es-module",
     "check-dependencies": "dependency-check package.json --unused --no-dev --ignore-module coveralls --ignore-module esm",
     "build": "node ./build.js",
+    "build-esm": "rollup -c",
     "lint": "run-p lint-js lint-markdown",
     "lint-js": "eslint '**/*.{js,mjs}'",
     "lint-markdown": "find docs -type f -name '*.md' ! -name 'changelog.md' | xargs markdownlint",
@@ -45,6 +46,7 @@
     "lodash.get": "^4.4.2",
     "lolex": "^2.6.0",
     "nise": "^1.3.3",
+    "rollup": "^0.59.3",
     "supports-color": "^5.4.0",
     "type-detect": "^4.0.8"
   },
@@ -69,6 +71,7 @@
     "proxyquire-universal": "^1.0.8",
     "proxyquireify": "^3.2.1",
     "rimraf": "^2.5.3",
+    "rollup-plugin-commonjs": "^9.1.3",
     "samsam": "^1.3.0"
   },
   "files": [

rollup.config.js

@@ -0,0 +1,46 @@
+// rollup.config.js
+import commonjs from "rollup-plugin-commonjs";
+//import nodeResolve from "rollup-plugin-node-resolve";
+
+export default {
+    input: "./lib/sinon.js",
+    output: {
+        file: "pkg/bundle-esm.js",
+        format: "esm"
+    },
+    plugins: [
+        //nodeResolve({
+        //jsnext: true,
+        //main: true
+        //}),
+
+        commonjs({
+            // non-CommonJS modules will be ignored, but you can also
+            // specifically include/exclude files
+            //include: "node_modules/**", // Default: undefined
+            //exclude: ["node_modules/foo/**", "node_modules/bar/**"], // Default: undefined
+            // these values can also be regular expressions
+            // include: /node_modules/
+
+            // search for files other than .js files (must already
+            // be transpiled by a previous plugin!)
+            //extensions: [".js", ".coffee"], // Default: [ '.js' ]
+
+            // if true then uses of `global` won't be dealt with by this plugin
+            ignoreGlobal: false, // Default: false
+
+            // if false then skip sourceMap generation for CommonJS modules
+            sourceMap: false // Default: true
+
+            // explicitly specify unresolvable named exports
+            // (see below for more details)
+            //namedExports: { "./module.js": ["foo", "bar"] }, // Default: undefined
+
+            // sometimes you have to leave require statements
+            // unconverted. Pass an array containing the IDs
+            // or a `id => boolean` function. Only use this
+            // option if you know what you're doing!
+            //ignore: ["conditional-runtime-dependency"]
+        })
+    ]
+};