Reject generic HTML block filters

Related feedback:
- https://github.com/uBlockOrigin/uBlock-issues/issues/1844

Generic HTML block filters will by highlighted as invalid and
rejected by uBO at compile time.

src/js/static-filtering-parser.js

@@ -324,6 +324,9 @@ const Parser = class {
             }
             this.flavorBits |= BITFlavorExtHTML;
             selector = selector.slice(1);
+            if ( (this.hasOptions() || this.isException()) === false ) {
+                this.flavorBits |= BITFlavorUnsupported;
+            }
         }
         // ##...
         else {