Place closing brace on its own line for comment-only blocks

When a block or object literal contains only block comment(s) and no
other tokens, the closing brace was kept on the same line as the last
comment, producing output such as:

    var a = {
        /* c */ }

This is not idempotent: running the beautifier on that output a second
time correctly moves the brace to its own line, so beautify(beautify(x))
differed from beautify(x).

The cause is in handle_end_block: empty_braces was computed solely from
last_token being the opening brace. Comments stored in comments_before
are emitted without updating last_token, so a brace-only-with-comment
block was treated as a genuinely empty {} and no newline was printed
before the closing brace. handle_start_block already guards the
symmetric case with !next_token.comments_before; this applies the same
guard to handle_end_block so the closing brace is placed on its own line
whenever the block contains comments.

Genuinely empty braces ({}) are unaffected and remain collapsed.

The change is applied to both the JavaScript and Python implementations,
with regression tests added to the shared test data.

Author: sarathfrancis90

js/src/javascript/beautifier.js

@@ -790,7 +790,7 @@ Beautifier.prototype.handle_end_block = function(current_token) {
     this.restore_mode();
   }
 
-  var empty_braces = this._flags.last_token.type === TOKEN.START_BLOCK;
+  var empty_braces = !current_token.comments_before && this._flags.last_token.type === TOKEN.START_BLOCK;
 
   if (this._flags.inline_frame && !empty_braces) { // try inline_frame (only set if this._options.braces-preserve-inline) first
     this._output.space_before_token = true;

python/jsbeautifier/javascript/beautifier.py

@@ -854,7 +854,10 @@ def handle_end_block(self, current_token):
         while self._flags.mode == MODE.Statement:
             self.restore_mode()
 
-        empty_braces = self._flags.last_token.type == TOKEN.START_BLOCK
+        empty_braces = (
+            current_token.comments_before is None
+            and self._flags.last_token.type == TOKEN.START_BLOCK
+        )
 
         # try inline_frame (only set if opt.braces-preserve-inline) first
         if self._flags.inline_frame and not empty_braces:

test/data/javascript/tests.js

@@ -3006,6 +3006,24 @@ exports.test_data = {
             'foo(o)'
           ]
         },
+        {
+          comment: 'object literal containing only a block comment - closing brace on its own line',
+          input: 'var a = {/* c */}',
+          output: [
+            'var a = {',
+            '    /* c */',
+            '}'
+          ]
+        },
+        {
+          comment: 'block statement containing only a block comment - closing brace on its own line',
+          input: 'if (x) {/* c */}',
+          output: [
+            'if (x) {',
+            '    /* c */',
+            '}'
+          ]
+        },
         {
           comment: '#713 and #964',
           unchanged: [