Reduce maximum length for numeric html entities

This is no longer recognized as an entity, according to commonmark 0.29 tests:
�

See also:
026ca8234b

lib/rules_inline/entity.js

@@ -8,7 +8,7 @@ var isValidEntityCode = require('../common/utils').isValidEntityCode;
 var fromCodePoint     = require('../common/utils').fromCodePoint;
 
 
-var DIGITAL_RE = /^&#((?:x[a-f0-9]{1,8}|[0-9]{1,8}));/i;
+var DIGITAL_RE = /^&#((?:x[a-f0-9]{1,6}|[0-9]{1,7}));/i;
 var NAMED_RE   = /^&([a-z][a-z0-9]{1,31});/i;
 
 

test/fixtures/markdown-it/commonmark_extras.txt

@@ -485,3 +485,13 @@ Coverage. Various tags not interrupting blockquotes because of indentation:
 # not a heading</p>
 </blockquote>
 .
+
+Coverage, entities with code > 10FFFF. Made this way for compatibility with commonmark.js.
+.
+&#x110000;
+
+&#x1100000;
+.
+<p>�</p>
+<p>&amp;#x1100000;</p>
+.