Handle CDATA unintentionally treated as a conditional comment

src/htmlparser.js

@@ -140,6 +140,17 @@ function HTMLParser(html, handler) {
           }
         }
 
+        // Treat <![CDATA[...]]> as a comment for backward compatibility. It was
+        // was unintentionally parsed as a conditional comment before
+        // https://github.com/kangax/html-minifier/pull/1162.
+        if (html.startsWith('<![CDATA[')) {
+          var cdataEnd = html.indexOf(']]>');
+          handler.comment(html.substring(2, cdataEnd + 2), true /* non-standard */);
+          html = html.substring(cdataEnd + 3);
+          prevTag = '';
+          continue;
+        }
+
         // https://en.wikipedia.org/wiki/Conditional_comment#Downlevel-revealed_conditional_comment
         if (/^<!\[/.test(html)) {
           var conditionalEnd = html.indexOf(']>');

tests/minifier.js

@@ -623,6 +623,26 @@ QUnit.test('collapsing space in conditional comments', function(assert) {
   }), output);
 });
 
+QUnit.test('treat CDATA as comments for backward compatibility', function(assert) {
+  var input;
+
+  input = '<![CDATA[line 1\nline 2]]>';
+  assert.equal(minify(input), input);
+  assert.equal(minify(input, { removeComments: true }), '');
+  input = '<p><![CDATA[line 1\nline 2]]></p>';
+  assert.equal(minify(input), input);
+  assert.equal(minify(input, { removeComments: true }), '<p></p>');
+
+  input = '<![CDATA[]]>';
+  assert.equal(minify(input), input);
+  assert.equal(minify(input, { removeComments: true }), '');
+
+  // https://github.com/kangax/html-minifier/issues/1161
+  input = '<![CDATA[___]><-___]]>';
+  assert.equal(minify(input), input);
+  assert.equal(minify(input, { removeComments: true }), '');
+});
+
 QUnit.test('remove comments from scripts', function(assert) {
   var input, output;