Nested block comments

Problem
-------
Nested block comments are not parsed, e.g.
```
/* /* */ */
```

Solution
-------
Leave $.comment for single-line comments.
Introduce $.block_comment for block-comments.
Make $.block_comment out of several tokens to be able to detect nested
block comments

Author: susliko

corpus/comments.txt

@@ -0,0 +1,33 @@
+================================================================================
+Single line comments
+================================================================================
+
+// comment 1
+// comment 2
+
+--------------------------------------------------------------------------------
+
+(compilation_unit
+  (comment)
+  (comment))
+
+================================================================================
+Block comments
+================================================================================
+/**/
+/** comment 1
+ * /* comment 2
+ *  /* / * * /comment 3 */
+ // comment 4
+ * @param
+ *  */
+*/
+
+--------------------------------------------------------------------------------
+
+(compilation_unit
+  (block_comment)
+  (block_comment
+    (block_comment
+      (block_comment)
+      (comment))))

corpus/expressions.txt

@@ -76,7 +76,7 @@ class C {
                   (identifier)
                   (operator_identifier)
                   (integer_literal)))))
-          (comment)
+          (block_comment)
           (call_expression
             (field_expression
               (identifier)
@@ -813,7 +813,7 @@ class C {
               (identifier)
               (identifier))
             (comment)
-            (comment)
+            (block_comment)
             (identifier)))))))
 
 ================================================================================

grammar.js

@@ -27,7 +27,8 @@ module.exports = grammar({
 
   extras: $ => [
     /\s/,
-    $.comment
+    $.comment,
+    $.block_comment,
   ],
 
   supertypes: $ => [
@@ -1294,7 +1295,7 @@ module.exports = grammar({
     wildcard: $ => '_',
 
     /**
-     * Regex patterns created to avoid matching // comments.
+     * Regex patterns created to avoid matching // comments and /* comment starts.
      * This could technically match illeagal tokens such as val ?// = 1
      */
     operator_identifier: $ => token(choice(
@@ -1309,8 +1310,8 @@ module.exports = grammar({
       seq(
         // opchar
         /[\-!#%&*+\/\\:<=>?@\u005e\u007c~\p{Sm}\p{So}]/,
-        // opchar minus slash
-        /[\-!#%&*+\\:<=>?@\u005e\u007c~\p{Sm}\p{So}]/,
+        // opchar minus slash and asterisk
+        /[\-!#%&+\\:<=>?@\u005e\u007c~\p{Sm}\p{So}]/,
         // opchar*
         repeat(/[\-!#%&*+\/\\:<=>?@\u005e\u007c~\p{Sm}\p{So}]/),
       ),
@@ -1520,14 +1521,14 @@ module.exports = grammar({
       repeat1($.guard),
     ),
 
-    comment: $ => token(choice(
-      seq('//', /.*/),
-      seq(
-        '/*',
-        /[^*]*\*+([^/*][^*]*\*+)*/,
-        '/'
-      )
-    ))
+    comment: $ => token(seq('//', /.*/)),
+
+    block_comment: $ => seq(
+      token('/*'),
+      repeat(token(/./)),
+      token('*/')
+    ),
+    
   }
 })