Make transformers more straightforward

src/utils/transformBundle.js

@@ -9,7 +9,7 @@ export default function transformBundle ( source, transformers ) {
 	}
 
 	return transformers.reduce( ( previous, transformer ) => {
-		let result = transformer( previous );
+		let result = transformer( previous.code, previous.map );
 
 		if ( result == null ) return previous;
 

test/form/transform-bundle-plugin/_config.js

@@ -3,13 +3,13 @@ module.exports = {
 	options: {
 		plugins: [
 			{
-				transformBundle: function (result) {
+				transformBundle: function (code) {
 					return '/* first plugin */';
 				}
 			},
 			{
-				transformBundle: function (result) {
-					return result.code + '\n/* second plugin */';
+				transformBundle: function (code) {
+					return code + '\n/* second plugin */';
 				}
 			}
 		]

test/sourcemaps/transform-bundle/_config.js

@@ -9,17 +9,17 @@ module.exports = {
 	options: {
 		plugins: [
 			{
-				transformBundle: function ( source ) {
+				transformBundle: function ( code, map ) {
 					var options = { fromString: true };
 
-					if ( source.map != null ) {
-						options.inSourceMap = source.map;
+					if ( map != null ) {
+						options.inSourceMap = map;
 						options.outSourceMap = "out";
 					}
 
-					var result = uglify.minify( source.code, options );
+					var result = uglify.minify( code, options );
 
-					if (source.map != null) {
+					if ( map != null ) {
 						result.code = result.code.slice( 0, -25 );
 					}