refactor(uglifyjs): change default config to be more specific and supply the toplevel option

Author: danbucholtz

config/uglifyjs.config.js

@@ -11,7 +11,11 @@ module.exports = {
   /**
    * compress: uglify 2's compress option
    */
-  compress: true,
+  compress: {
+    unused: true,
+    dead_code: true,
+    toplevel: true
+  },
 
   /**
    * comments: uglify 2's comments option

src/uglifyjs.ts

@@ -63,11 +63,7 @@ export function uglifyjsWorkerImpl(context: BuildContext, uglifyJsConfig: Uglify
 
 function runUglifyInternal(uglifyJsConfig: UglifyJsConfig): uglify.MinifyOutput {
   return uglify.minify(uglifyJsConfig.sourceFile, {
-    compress: {
-      unused: true,
-      dead_code: true,
-      toplevel: true
-    },
+    compress: uglifyJsConfig.compress,
     mangle: uglifyJsConfig.mangle,
     inSourceMap : uglifyJsConfig.inSourceMap,
     outSourceMap: uglifyJsConfig.outSourceMap