no line terminator after contextual async keyword

acorn.js

@@ -2609,6 +2609,13 @@
 
           // normal functions
           if (tokType === _function) {
+            if (isStatement) {
+              // no line terminator after `async` contextual keyword
+              if (tokType === _semi || canInsertSemicolon()) {
+                return id;
+              }
+            }
+
             next();
             return parseFunction(node, isStatement, true);
           }

package.json

@@ -2,7 +2,7 @@
   "name": "acorn-6to5",
   "description": "Acorn fork used by 6to5",
   "main": "acorn.js",
-  "version": "0.11.1-8",
+  "version": "0.11.1-9",
   "maintainers": [
     {
       "name": "Marijn Haverbeke",