Make sure await in class field initializers is checked properly

FIX: Fix an issue where `await` expressions in class field initializers were
inappropriately allowed.

Closes #1334

Author: marijnh

acorn/src/state.js

@@ -104,9 +104,10 @@ export class Parser {
   get inAsync() { return (this.currentVarScope().flags & SCOPE_ASYNC) > 0 && !this.currentVarScope().inClassFieldInit }
 
   get canAwait() {
+    if (this.currentThisScope().inClassFieldInit) return false
     for (let i = this.scopeStack.length - 1; i >= 0; i--) {
       let scope = this.scopeStack[i]
-      if (scope.inClassFieldInit || scope.flags & SCOPE_CLASS_STATIC_BLOCK) return false
+      if (scope.flags & SCOPE_CLASS_STATIC_BLOCK) return false
       if (scope.flags & SCOPE_FUNCTION) return (scope.flags & SCOPE_ASYNC) > 0
     }
     return (this.inModule && this.options.ecmaVersion >= 13) || this.options.allowAwaitOutsideFunction

test/tests-asyncawait.js

@@ -3540,3 +3540,5 @@ testFail("async() => await (5) ** 6", "Unexpected token (1:21)", {ecmaVersion: 8
 testFail("4 + async() => 2", "Unexpected token (1:12)", {ecmaVersion: 8, loose: false})
 
 testFail("async function𝐬 f() {}", "Unexpected token (1:17)", {ecmaVersion: 8})
+
+testFail("async () => class { x = await 1 }", "Cannot use 'await' as identifier inside an async function (1:24)", {ecmaVersion: 2024})