feat(plugin-legacy): support additionalModernPolyfills (#16514)

Author: iammminzzy

packages/plugin-legacy/README.md

@@ -74,7 +74,11 @@ npm add -D terser
 
   Add custom imports to the legacy polyfills chunk. Since the usage-based polyfill detection only covers ES language features, it may be necessary to manually specify additional DOM API polyfills using this option.
 
-  Note: if additional polyfills are needed for both the modern and legacy chunks, they can simply be imported in the application source code.
+### `additionalModernPolyfills`
+
+- **Type:** `string[]`
+
+  Add custom imports to the modern polyfills chunk. Since the usage-based polyfill detection only covers ES language features, it may be necessary to manually specify additional DOM API polyfills using this option.
 
 ### `modernPolyfills`
 

packages/plugin-legacy/src/index.ts

@@ -166,6 +166,11 @@ function viteLegacyPlugin(options: Options = {}): Plugin[] {
       )
     })
   }
+  if (Array.isArray(options.additionalModernPolyfills)) {
+    options.additionalModernPolyfills.forEach((i) => {
+      modernPolyfills.add(i)
+    })
+  }
   if (Array.isArray(options.polyfills)) {
     options.polyfills.forEach((i) => {
       if (i.startsWith(`regenerator`)) {

packages/plugin-legacy/src/types.ts

@@ -12,6 +12,7 @@ export interface Options {
    */
   polyfills?: boolean | string[]
   additionalLegacyPolyfills?: string[]
+  additionalModernPolyfills?: string[]
   /**
    * default: false
    */