Update terser to v5.18.2 and verify optional chaining support

Fixes: #15827

Author: sbc100

test/optimizer/applyImportAndExportNameChanges2-output.js

@@ -264,7 +264,7 @@ var imports = {
 
 var ___errno_location, _llvm_bswap_i32, _main, _memcpy, _memset, dynCall_ii, dynCall_iiii;
 
-WebAssembly.instantiate(Module["wasm"], imports).then(output => {
+WebAssembly.instantiate(Module["wasm"], imports).then((output => {
  var asm = output.instance.exports;
  ___errno_location = asm["j"];
  _llvm_bswap_i32 = asm["k"];
@@ -275,4 +275,4 @@ WebAssembly.instantiate(Module["wasm"], imports).then(output => {
  dynCall_iiii = asm["p"];
  initRuntime(asm);
  ready();
-});
+}));

test/optimizer/minimal-runtime-applyDCEGraphRemovals-output.js

@@ -5,14 +5,14 @@ var wasmImports = {
  "save2": 2
 };
 
-WebAssembly.instantiate(Module["wasm"], imports).then(output => {
+WebAssembly.instantiate(Module["wasm"], imports).then((output => {
  asm = output.instance.exports;
  expD1 = asm["expD1"];
  expD2 = asm["expD2"];
  expD3 = asm["expD3"];
  initRuntime(asm);
  ready();
-});
+}));
 
 expD1;
 

test/other/metadce/test_metadce_minimal_pthreads.jssize

@@ -1 +1 @@
-15050
+15052

third_party/terser/README.md

@@ -1,5 +1,5 @@
-Bundled version of terser 4.1.0 with emscripten patches
-=======================================================
+Bundled version of terser 5.18.2 with emscripten patches
+========================================================
 
 We maintain a few downstream patches to terser which means we can't use the
 version published in npm.
@@ -13,5 +13,5 @@ To make changes to this code please submit patches to
 https://github.com/emscripten-core/terser/ and then re-create this bundle
 using the following steps:
 
-  $ npx rollup -c
-  $ cp dist/bundle.js $EMSCRIPTEN_ROOT/third_party/terser/terser.js
+  $ CI=1 npx rollup -c
+  $ cp dist/bundle.min.js $EMSCRIPTEN_ROOT/third_party/terser/terser.js

third_party/terser/terser.js

@@ -1945,24 +1945,16 @@ function reattachComments(ast, comments) {
       symbols[j].start.comments_before = [];
     }
     symbols[j].start.comments_before.push(
-      new terser.AST_Token({
-        end: undefined,
-        quote: undefined,
-        raw: undefined,
-        file: '0',
-        comments_after: undefined,
-        comments_before: undefined,
-        nlb: false,
-        endpos: undefined,
-        endcol: undefined,
-        endline: undefined,
-        pos: undefined,
-        col: undefined,
-        line: undefined,
-        value: comments[i].value,
-        type: comments[i].type == 'Line' ? 'comment' : 'comment2',
-        flags: 0,
-      })
+      new terser.AST_Token(
+        comments[i].type == 'Line' ? 'comment' : 'comment2',
+        comments[i].value,
+        undefined,
+        undefined,
+        false,
+        undefined,
+        undefined,
+        '0'
+      )
     );
   }
 }

tools/acorn-optimizer.js

@@ -223,7 +223,7 @@ function optPassMergeVarInitializationAssignments(ast) {
 }
 
 function runOnJsText(js, pretty = false) {
-  const ast = acorn.parse(js, {ecmaVersion: 6});
+  const ast = acorn.parse(js, {ecmaVersion: 2020});
 
   optPassSimplifyModuleInitialization(ast);
   optPassRemoveRedundantOperatorNews(ast);
@@ -255,7 +255,7 @@ let numTestFailures = 0;
 function test(input, expected) {
   const observed = runOnJsText(input);
   if (observed != expected) {
-    console.error(`Input: ${input}\nobserved: ${observed}\nexpected: ${expected}\n`);
+    console.error(`ERROR: Input: ${input}\nobserved: ${observed}\nexpected: ${expected}\n`);
     ++numTestFailures;
   } else {
     console.log(`OK: ${input} -> ${expected}`);
@@ -279,7 +279,7 @@ function runTests() {
   test("new function(a) {new TextDecoder(a);}('utf8');", '');
   test(
     'WebAssembly.instantiate(c.wasm,{}).then((a) => {new Int8Array(b);});',
-    'WebAssembly.instantiate(c.wasm,{}).then(a=>{});'
+    'WebAssembly.instantiate(c.wasm,{}).then((a=>{}));'
   );
   test('let x=new Uint16Array(a);', 'let x=new Uint16Array(a);');
 
@@ -305,6 +305,9 @@ function runTests() {
   // Test that arrays containing nulls don't cause issues
   test('[,];', '[,];');
 
+  // Test optional chaining operator
+  test('console?.log("");', 'console?.log("");');
+
   process.exit(numTestFailures);
 }