Only already normalized CSS selectors can be fast path-compiled

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/2730

CSS selectors used in cosmetic filtering are normalized in order
to ignore non-functional differences. For instance:

    example.org##body      p
    example.org#@#body p

The first cosmetic filter should be excepted by the second one,
but this was not the case because the fast path use to compile
common CSS selectors was not causing normalization to take
place.

The fix is to ensure that the fast path used to compile most
common CSS selectors is taken only when in presence of already
normalized CSS selectors.

src/js/static-filtering-parser.js

@@ -793,7 +793,6 @@ export class AstFilterParser {
         this.reHostnameLabel = /[^.]+/g;
         this.reResponseheaderPattern = /^\^responseheader\(.*\)$/;
         this.rePatternScriptletJsonArgs = /^\{.*\}$/;
-        // TODO: mind maxTokenLength
         this.reGoodRegexToken = /[^\x01%0-9A-Za-z][%0-9A-Za-z]{7,}|[^\x01%0-9A-Za-z][%0-9A-Za-z]{1,6}[^\x01%0-9A-Za-z]/;
         this.reBadCSP = /(?:=|;)\s*report-(?:to|uri)\b/;
         this.reOddTrailingEscape = /(?:^|[^\\])(?:\\\\)*\\$/;
@@ -3028,7 +3027,7 @@ class ExtSelectorCompiler {
             `${cssClassOrId}(?:${cssClassOrId})*(?:${cssAttribute})*` + '|' +
             `${cssAttribute}(?:${cssAttribute})*` +
             ')';
-        const cssCombinator = '(?:\\s+|\\s*[+>~]\\s*)';
+        const cssCombinator = '(?: | [+>~] )';
         this.reCommonSelector = new RegExp(
             `^${cssSimple}(?:${cssCombinator}${cssSimple})*$`
         );