Publish the development version to npm

A major version of Esprima is released (and published to npm) only when there is a breaking change. Typically, this happens when Esprima parser needs to support the most recent ECMAScript specification (final version, not the drafts). Since ECMA-262 switched to an annual release, Esprima major version bumps tend to follow this as well.

Language tools which intentionally (often with an explicit experimental warning) want to understand a new proposed ECMAScript syntax, even before the syntax is finalized in the official specification, can not always wait until a new major version of Esprima is available. To support such tools, the development version of Esprima should be published to npm. As an additional bonus, it gives a bigger window of opportunity to give feedback before the stable version of Esprima is released.

Review Esprima's existing release and npm publication process; the issue names no files or tests, so first locate those entry points. Done means a development version of Esprima can be published to npm before the next stable major release.