clean up explosion of module declarations, remove and inherit comments when taking off the declaration - fixes #1583

test/core/fixtures/transformation/es6.modules/comments-explosion/actual.js

@@ -0,0 +1,4 @@
+bar();
+
+// bar
+export function foo() {}

test/core/fixtures/transformation/es6.modules/comments-explosion/expected.js

@@ -0,0 +1,8 @@
+"use strict";
+
+export { foo };
+bar();
+
+// bar
+
+function foo() {}

test/core/fixtures/transformation/es6.modules/comments-explosion/options.json

@@ -0,0 +1,4 @@
+{
+  "blacklist": ["es6.modules"],
+  "noCheckAst": true
+}