Preserve end-of-line comment for if statement without blocks (#12017)

* Print as dangling comments

* Add tests

* Add changelog

* Use symbol instead of string

changelog_unreleased/javascript/12017.md

@@ -0,0 +1,22 @@
+#### Preserve end-of-line comment for if statements without blocks (#12017 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+if (condition1) expression1; // comment A
+else if (condition2) expression2; // comment B
+else expression3; // comment C
+
+// Prettier stable
+if (condition1) expression1;
+// comment A
+else if (condition2) expression2;
+// comment B
+else expression3; // comment C
+
+// Prettier main
+if (condition1) expression1; // comment A
+else if (condition2) expression2; // comment B
+else expression3; // comment C
+
+```