Bump ecmascript patch version to republish compile-ecmascript plugin.

When the ecmascript package version was last bumped in
18e4c17, it appears that
babel-compiler@6.20.0 had not yet been published, so ecmascript was
published with a copy of that compiler plugin that did not support the
"env" property of .babelrc files (#8963).

Bumping again and republishing in hopes of fixing that problem.

packages/ecmascript/package.js

@@ -1,6 +1,6 @@
 Package.describe({
   name: 'ecmascript',
-  version: '0.8.2',
+  version: '0.8.3',
   summary: 'Compiler plugin that supports ES2015+ in all .js files',
   documentation: 'README.md'
 });