ESM bundle build optimization (#3985)

- Ditch the `global` bundle in favor of `prism.global.ts` that is output to `prism.js` (see below)
- Remove chunks

Rel to #3984.
The global bundle generated only one file (`prism.js` from `auto-start.ts`) in the IIFE format. When `prism.js` was included on a web page, it created an instance of Prism (as it should) and exposed it. The plugins and languages _were not_ part of the global bundle. When we included one of those plugins, we imported an instance of Prism (`globalPrism`) from a module that is _part of another bundle_, which the global bundle was unaware of. During that process, a new instance of Prism was created, and the imported plugin attached itself to that instance, not the one we had expected (the first one instantiated). The global bundle and the plugins didn't share the same modules, since they were parts of different bundles. This should be fixed now.

Co-authored-by: Lea Verou <[email protected]>

Author: DmitrySharabin

scripts/build.ts

@@ -364,6 +364,7 @@ async function buildTypes () {
 async function buildJS () {
 	const input: Record<string, string> = {
 		'index': path.join(SRC_DIR, 'index.ts'),
+		'prism': path.join(SRC_DIR, 'prism.global.ts'),
 		'shared': path.join(SRC_DIR, 'shared.ts'),
 	};
 	for (const id of languageIds) {
@@ -386,7 +387,6 @@ async function buildJS () {
 
 	const defaultOutputOptions: OutputOptions = {
 		dir: './dist',
-		chunkFileNames: '_chunks/[name]-[hash].js',
 		validate: true,
 		sourcemap: 'hidden',
 	};
@@ -413,21 +413,6 @@ async function buildJS () {
 				dir: './dist/cjs',
 			},
 		},
-		global: {
-			rollupOptions: {
-				...defaultRollupOptions,
-				input: {
-					'prism': path.join(SRC_DIR, 'auto-start.ts'),
-				},
-			},
-			outputOptions: {
-				...defaultOutputOptions,
-				format: 'iife',
-				name: 'Prism',
-				exports: 'default',
-				extend: true,
-			},
-		},
 	};
 
 	try {

src/prism.global.ts

@@ -0,0 +1,2 @@
+// In browser and imported via non-ESM
+import('./index.js').then(({ default: prism }) => ((globalThis as any).Prism = prism));