fix(parser): fix async assignment in comma expression

src/parser.ts

@@ -1100,15 +1100,6 @@ export function parseAsyncArrowOrAsyncFunctionDeclaration(
    */
 
   expr = parseMemberOrUpdateExpression(parser, context, expr, 0, 0, start, line, column);
-  /** Sequence expression
-   *
-   * Note: The comma operator leads to a sequence expression which is not equivalent
-   * to the ES Expression, but it's part of the ESTree specs:
-   *
-   * https://github.com/estree/estree/blob/master/es5.md#sequenceexpression
-   *
-   */
-  if (parser.token === Token.Comma) expr = parseSequenceExpression(parser, context, 0, start, line, column, expr);
 
   /** AssignmentExpression :
    *
@@ -1120,6 +1111,16 @@ export function parseAsyncArrowOrAsyncFunctionDeclaration(
 
   parser.assignable = AssignmentKind.Assignable;
 
+  /** Sequence expression
+   *
+   * Note: The comma operator leads to a sequence expression which is not equivalent
+   * to the ES Expression, but it's part of the ESTree specs:
+   *
+   * https://github.com/estree/estree/blob/master/es5.md#sequenceexpression
+   *
+   */
+  if (parser.token === Token.Comma) expr = parseSequenceExpression(parser, context, 0, start, line, column, expr);
+
   /**
    * ExpressionStatement[Yield, Await]:
    *   [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]Expression[+In, ?Yield, ?Await]

test/parser/declarations/functions.ts

@@ -397,6 +397,7 @@ describe('Declarations - Function', () => {
     'function f() { function await() { } }',
     'function f() { const await = 10; }',
     'function f(a = async function (x) { await x; }) { a(); } f();',
+    'function f() {async = 1, a = 2;}',
     'function f() {var async = 1; return async;}',
     'function f() {let async = 1; return async;}',
     'function f() {const async = 1; return async;}',

test/parser/miscellaneous/pass.ts

@@ -2834,6 +2834,7 @@ after = err;
     'x = await(y);',
     'class X { await() {} }',
     'let async = await;',
+    'async = 1, b = 2;',
     'x = { await: false }',
     'yield[100]',
     `async