Add comments property to babylon.parseExpression() result

src/parser/expression.js

@@ -73,6 +73,7 @@ export default class ExpressionParser extends LValParser {
     if (!this.match(tt.eof)) {
       this.unexpected();
     }
+    expr.comments = this.state.comments;
     return expr;
   }
 

test/expressions/is-expression-babylon/pass/5/expected.json

@@ -32,5 +32,23 @@
         }
       }
     }
+  ],
+  "comments": [
+    {
+      "type": "CommentLine",
+      "value": " my comment",
+      "start": 4,
+      "end": 17,
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 4
+        },
+        "end": {
+          "line": 1,
+          "column": 17
+        }
+      }
+    }
   ]
 }