DevTools: support pretty-print of async/await

third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js

Index: third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js
diff --git a/third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js b/third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js
index 85ed624fdc86acb06d77038392cbf87b9afc3672..640ddb4dd534197f0f54b0f62a78dca769d07885 100644
--- a/third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js
+++ b/third_party/WebKit/Source/devtools/front_end/formatter_worker/JavaScriptFormatter.js
@@ -51,7 +51,7 @@ FormatterWorker.JavaScriptFormatter = class {
     this._content = text.substring(this._fromOffset, this._toOffset);
     this._lastLineNumber = 0;
     this._tokenizer = new FormatterWorker.AcornTokenizer(this._content);
-    var ast = acorn.parse(this._content, {ranges: false, ecmaVersion: 7});
+    var ast = acorn.parse(this._content, {ranges: false, ecmaVersion: 8});
     var walker = new FormatterWorker.ESTreeWalker(this._beforeVisit.bind(this), this._afterVisit.bind(this));
     walker.walk(ast);
   }