fix: avoid poisoning global scope

packages/shiki/src/global.d.ts

@@ -1 +1,20 @@
-declare var __BROWSER__: boolean
+declare global {
+  var __BROWSER__: boolean
+
+  // These will not be defined for Node which don't have "DOM" in their lib.
+  // So declare the minimal interface we need.
+  // They are defined here and not in `loader.ts` to avoid getting injected in the built code.
+  interface Window {
+    WorkerGlobalScope: any
+  }
+
+  var self: Window & typeof globalThis
+  function fetch(url: string): Promise<Response>
+  interface Response {
+    json(): Promise<any>
+    text(): Promise<any>
+  }
+}
+
+// This export is here so that all variables above would be added to the global scope
+export {}

packages/shiki/src/loader.ts

@@ -1,23 +1,11 @@
+/// <reference path="./global.d.ts" />
+
 import { join, dirpathparts } from './utils'
 import type { IGrammar, IOnigLib, IRawTheme } from 'vscode-textmate'
 import { loadWASM, createOnigScanner, createOnigString } from 'vscode-oniguruma'
 import { parse, ParseError } from 'jsonc-parser'
 import type { IShikiTheme } from './types'
 
-// These will not be defined for Node which don't have "DOM" in their lib.
-// So declare the minimal interface we need.
-declare global {
-  interface Window {
-    WorkerGlobalScope: any
-  }
-  var self: Window & typeof globalThis
-  function fetch(url: string): Promise<Response>
-  interface Response {
-    json(): Promise<any>
-    text(): Promise<any>
-  }
-}
-
 export const isWebWorker =
   typeof self !== 'undefined' && typeof self.WorkerGlobalScope !== 'undefined'
 export const isNode =