LibWeb: Fix 'Comment end state' in HTML Tokenizer

Also, update the expected hash in the LibWeb TestHTMLTokenizer
regression test.

This is due to the "This comment has a few too many dashes." comment
token being updated.

Tests/LibWeb/TestHTMLTokenizer.cpp

@@ -206,5 +206,5 @@ TEST_CASE(regression)
     auto file_contents = file.value()->read_all();
     auto tokens = run_tokenizer(file_contents);
     u32 hash = hash_tokens(tokens);
-    EXPECT_EQ(hash, 3215459107u);
+    EXPECT_EQ(hash, 710375345u);
 }

Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.cpp

@@ -1483,7 +1483,7 @@ _StartOfFunction:
                 }
                 ANYTHING_ELSE
                 {
-                    m_current_builder.append('-');
+                    m_current_builder.append("--");
                     RECONSUME_IN(Comment);
                 }
             }