Add tests for multiple comments (#13890)

Close https://github.com/prettier/prettier/issues/3105

tests/format/js/comments/__snapshots__/jsfmt.spec.js.snap

@@ -3808,6 +3808,55 @@ y;
 ================================================================================
 `;
 
+exports[`multi-comments-2.js - {"semi":false} format 1`] = `
+====================================options=====================================
+parsers: ["babel", "flow", "typescript"]
+printWidth: 80
+semi: false
+                                                                                | printWidth
+=====================================input======================================
+  const x = 0;
+  
+  /* istanbul ignore if */ // debug case currently not triggered
+  if (true) {
+    x;
+  }
+
+=====================================output=====================================
+const x = 0
+
+/* istanbul ignore if */ // debug case currently not triggered
+if (true) {
+  x
+}
+
+================================================================================
+`;
+
+exports[`multi-comments-2.js format 1`] = `
+====================================options=====================================
+parsers: ["babel", "flow", "typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+  const x = 0;
+  
+  /* istanbul ignore if */ // debug case currently not triggered
+  if (true) {
+    x;
+  }
+
+=====================================output=====================================
+const x = 0;
+
+/* istanbul ignore if */ // debug case currently not triggered
+if (true) {
+  x;
+}
+
+================================================================================
+`;
+
 exports[`multi-comments-on-same-line.js - {"semi":false} format 1`] = `
 ====================================options=====================================
 parsers: ["babel", "flow", "typescript"]

tests/format/js/comments/multi-comments-2.js

@@ -0,0 +1,6 @@
+  const x = 0;
+  
+  /* istanbul ignore if */ // debug case currently not triggered
+  if (true) {
+    x;
+  }