Use null at the end of {{{ }}} code blocks that are side-effect only. NFC (#18324)

This, IMHO, is more reasonable than creating an IIFE than returns
null.

Author: sbc100

src/library_html5_webgpu.js

@@ -1,4 +1,4 @@
-{{{ (function() {
+{{{
   // Helper functions for code generation
   global.html5_gpu = {
     makeImportExport: function(snake_case, CamelCase) {
@@ -17,8 +17,8 @@
       return s;
     },
   };
-  return null;
-})(); }}}
+  null;
+}}}
 
 
 var LibraryHTML5WebGPU = {

src/library_wasm_worker.js

@@ -1,6 +1,9 @@
-{{{ (function() { global.captureModuleArg = function() { return MODULARIZE ? '' : 'self.Module=d;'; }; return null; })(); }}}
-{{{ (function() { global.instantiateModule = function() { return MODULARIZE ? `${EXPORT_NAME}(d);` : ''; }; return null; })(); }}}
-{{{ (function() { global.instantiateWasm = function() { return MINIMAL_RUNTIME ? '' : 'd[`instantiateWasm`]=(i,r)=>{var n=new WebAssembly.Instance(d[`wasm`],i);r(n,d[`wasm`]);return n.exports};'; }; return null; })(); }}}
+{{{
+  global.captureModuleArg = () => MODULARIZE ? '' : 'self.Module=d;';
+  global.instantiateModule = () => MODULARIZE ? `${EXPORT_NAME}(d);` : '';
+  global.instantiateWasm = () => MINIMAL_RUNTIME ? '' : 'd[`instantiateWasm`]=(i,r)=>{var n=new WebAssembly.Instance(d[`wasm`],i);r(n,d[`wasm`]);return n.exports};';
+  null;
+}}}
 
 #if WASM_WORKERS
 

src/library_webgl.js

@@ -9,11 +9,12 @@
 {{{ GL_POOL_TEMP_BUFFERS_SIZE = 2*9*16 }}} // = 288
 
 {{{
-  global.isCurrentContextWebGL2 = function isCurrentContextWebGL2() {
+  global.isCurrentContextWebGL2 = () => {
     if (MIN_WEBGL_VERSION >= 2) return 'true';
     if (MAX_WEBGL_VERSION <= 1) return 'false';
     return 'GL.currentContext.version >= 2';
   }
+  null;
 }}}
 
 var LibraryGL = {

src/library_webgpu.js

@@ -21,7 +21,7 @@
  *   (requires WebGPU to be available - otherwise the test will skip itself and pass)
  */
 
-{{{ (function() {
+{{{
   // Helper functions for code generation
   global.gpu = {
     makeInitManager: function(type) {
@@ -157,8 +157,8 @@
       VertexBufferNotUsed: 2,
     },
   };
-  return null;
-})(); }}}
+  null;
+}}}
 
 var LibraryWebGPU = {
   $WebGPU__postset: 'WebGPU.initManagers();',