rollup: speed up dev build by bypassing babel and terser plugins

Brings it down from ~3 secs on my machine to ~600 ms.

This also allows for debuggers, and essentially eliminates the need
for source maps on your local (though we should probably still look
into them for prod).

Change-Id: I4c164b409b2c327e439e1524d4a898693bd8d907

package.json

@@ -3,7 +3,7 @@
 	"private": true,
 	"scripts": {
 		"start": "rollup -c --watch",
-		"build": "rollup -c",
+		"build": "rollup -c --environment BUILD:production",
 		"test": "npm run test:lint && npm run test:unit && npm run check-built-assets",
 		"test:lint": "npm run test:lint:styles && npm run test:lint:js && npm run test:lint:i18n",
 		"test:lint:js": "eslint --cache .",

rollup.config.js

@@ -5,6 +5,8 @@ const copy = require( 'rollup-plugin-copy' );
 const babel = require( '@rollup/plugin-babel' );
 const terser = require( '@rollup/plugin-terser' );
 
+const isProduction = process.env.BUILD === 'production';
+
 /**
  * Mapping of import paths to ResourceLoader module names.
  * See usage in 'plugins' below for explanation.
@@ -67,6 +69,12 @@ module.exports = [
 								`require("${ alias }")`,
 								`require("${ importAliases[ alias ] }")`
 							);
+							// Yuck, need to do the same with single apostrophes
+							// in the event terser is disabled such as during dev builds.
+							contents = contents.toString().replace(
+								`require('${ alias }')`,
+								`require('${ importAliases[ alias ] }')`
+							);
 						} );
 						return contents;
 					}
@@ -74,9 +82,9 @@ module.exports = [
 				hook: 'writeBundle'
 			} ),
 
-			babel( { babelHelpers: 'bundled' } ),
+			isProduction ? babel( { babelHelpers: 'bundled' } ) : null,
 
-			terser()
+			isProduction ? terser() : null
 		],
 
 		onwarn: ( warning, warn ) => {