Fix regex-like filter representation in logger

Related discussion:
- https://github.com/uBlockOrigin/uBlock-issues/issues/805#issuecomment-561500819

uBO was testing for regex-like plain patterns after
prepending `@@` in the case of exception filters, thus
preventing proper detection of regex-like plain
patterns. The filtering engine was not affected, only
the proper rendering of the filter in the logger was
affected.

src/js/static-net-filtering.js

@@ -223,9 +223,6 @@ const toLogDataInternal = function(categoryBits, tokenHash, iunit) {
     const domains = [];
     const logData = { pattern, regex, domains, options, isRegex: false };
     filterUnits[iunit].logData(logData);
-    if ( categoryBits & 0x001 ) {
-        logData.pattern.unshift('@@');
-    }
     if ( categoryBits & 0x002 ) {
         logData.options.unshift('important');
     }
@@ -246,6 +243,9 @@ const toLogDataInternal = function(categoryBits, tokenHash, iunit) {
     ) {
         raw += '*';
     }
+    if ( categoryBits & 0x001 ) {
+        raw = '@@' + raw;
+    }
     if ( domains.length !== 0 ) {
         options.push(`domain=${domains.join('|')}`);
     }