Add dist files, bundler integration tests

[katelynsills]

Still in progress, bugs remain

Description

This PR builds on #68 and generates three different dist files with rollup - an ES6 module version, a CommonJS version, and a UMD version. These are listed under pkg.module, pkg.main, and pkg.browser respectively.

This PR adds integration tests that run automatically with CircleCI to test that SES's dist files are usable with the main JavaScript bundlers and tools. We test SES with Webpack, Browserify, Rollup, Parcel, and a mocked version of what unpkg would provide after publishing the latest version to npm. There is a README.md in /integration-test with more detailed information.

Current Bugs

1. Webpack and Parcel seem to rename SES such that when a function that includes a call to SES is run within SES, it throws a ReferenceError. We may be able to turn this renaming off.

2. Right now the bundlers will error when they try to bundle our tests of the require() functionality because the bundler will not be able to find the modules unknown and foo As a partial fix, the test-require.js tests are not included in the test suite run by webpack and parcel, but they are tested in rollup, browserify, and unpkg. This prevents this error entirely, but it does mean that we will not catch future error related to the require functionality in webpack and parcel.

Considerations

We still need to test using the ES6 module version directly in the browser with type="module". This seems to require spinning up a small server on CircleCI.

Tests

• npm test to make sure normal tests still pass
• npm run build to build the dist files
• check that the dist files are ignored by git and eslint
• npm pack to check that the dist files are included in the npm tarball
• test the test_integration job locally with the CircleCI command line tool: circleci local execute --job test_integration

[warner]

3. Right now the bundlers will error when they try to bundle our tests of the require() functionality because the bundler will not be able to find the modules unknown and foo

We might try doing a const require2 = require; require2('unknown'). That trick may not work depending on how smart the bundling tools are, but it's worth a shot.

[katelynsills]

With the Realms shim fix, now works entirely with Browserify, Rollup, and the mock version of unpkg.

[katelynsills]

Replaced by #97