Support dynamic imports

[hoschi]

minimal.js

import('./myModule').then(myModule => console.log(myModule))

gives:

formatting > esformatter minimal.js
Error: minimal.js:1:6 Unexpected token, expected {
SyntaxError: Unexpected token, expected { (1:6)
    at Parser.pp$5.raise (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:4373:13)
    at Parser.pp.unexpected (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:1716:8)
    at Parser.pp.expect (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:1704:33)
    at Parser.pp$1.parseImportSpecifiers (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:2833:8)
    at Parser.parseImportSpecifiers (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:6080:13)
    at Parser.pp$1.parseImport (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:2803:10)
    at Parser.pp$1.parseStatement (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:1839:49)
    at Parser.parseStatement (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:5712:22)
    at Parser.pp$1.parseBlockBody (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:2223:21)
    at Parser.pp$1.parseTopLevel (/home/hoschi/repos/gis/formatting/node_modules/babylon/lib/index.js:1733:8)

which due to the old babylon version.