Extend matches-css() to support any pseudo-element

This commit deprecates matches-css-before() and matches-css-after(): these
should no longer be used once 1.45.0 is published and widespread. The
deprecated syntax will eventually be removed in some future.

The syntax of procedural operator matches-css() has been extended to also
be able to target pesudo elements. Examples:

Same as before:

    example.com##p:matches-css(opacity: 0.5)

This is the new way to target an `::after` pseudo-element:

    example.com##p:matches-css(after, content: Ads)

This is the new way to target a `::before` pseudo-element:

    example.com##p:matches-css(before, content: Ads)

The new syntax also means any valid pseudo-element can now be used as
a target:

    example.com##p:matches-css(first-letter, opacity: 0.5)

If the first argument does not match the pattern "property name: value",
then it will be deemed a pseudo-element to target, and the second argument
will be the "property name: value".

Related issue:
- AdguardTeam/ExtendedCss#150

src/js/contentscript-extra.js

@@ -81,6 +81,7 @@ class PSelectorMatchesCSSTask extends PSelectorTask {
     constructor(task) {
         super();
         this.name = task[1].name;
+        this.pseudo = task[1].pseudo ? `::${task[1].pseudo}` : null;
         let arg0 = task[1].value, arg1;
         if ( Array.isArray(arg0) ) {
             arg1 = arg0[1]; arg0 = arg0[0];
@@ -94,15 +95,19 @@ class PSelectorMatchesCSSTask extends PSelectorTask {
         }
     }
 }
-PSelectorMatchesCSSTask.prototype.pseudo = null;
-
 class PSelectorMatchesCSSAfterTask extends PSelectorMatchesCSSTask {
+    constructor(task) {
+        super(task);
+        this.pseudo = 'after';
+    }
 }
-PSelectorMatchesCSSAfterTask.prototype.pseudo = ':after';
 
 class PSelectorMatchesCSSBeforeTask extends PSelectorMatchesCSSTask {
+    constructor(task) {
+        super(task);
+        this.pseudo = 'before';
+    }
 }
-PSelectorMatchesCSSBeforeTask.prototype.pseudo = ':before';
 
 class PSelectorMatchesMediaTask extends PSelectorTask {
     constructor(task) {

src/js/static-filtering-parser.js

@@ -1560,6 +1560,13 @@ Parser.prototype.SelectorCompiler = class {
     }
 
     compileCSSDeclaration(s) {
+        let pseudo; {
+            const match = /^[a-z-]+,/.exec(s);
+            if ( match !== null ) {
+                pseudo = match[0].slice(0, -1);
+                s = s.slice(match[0].length).trim();
+            }
+        }
         const pos = s.indexOf(':');
         if ( pos === -1 ) { return; }
         const name = s.slice(0, pos).trim();
@@ -1576,7 +1583,7 @@ Parser.prototype.SelectorCompiler = class {
             regexDetails = '^' + value.replace(this.reEscapeRegex, '\\$&') + '$';
             this.regexToRawValue.set(regexDetails, value);
         }
-        return { name: name, value: regexDetails };
+        return { name, pseudo, value: regexDetails };
     }
 
     compileInteger(s, min = 0, max = 0x7FFFFFFF) {
@@ -1711,7 +1718,11 @@ Parser.prototype.SelectorCompiler = class {
                         value = `/${task[1].value}/`;
                     }
                 }
-                raw.push(`${task[0]}(${task[1].name}: ${value})`);
+                if ( task[1].pseudo ) {
+                    raw.push(`:matches-css(${task[1].pseudo}, ${task[1].name}: ${value})`);
+                } else {
+                    raw.push(`:matches-css(${task[1].name}: ${value})`);
+                }
                 break;
             case ':not':
             case ':if-not':
@@ -1907,9 +1918,9 @@ Parser.prototype.SelectorCompiler = class {
         case ':matches-css':
             return this.compileCSSDeclaration(args);
         case ':matches-css-after':
-            return this.compileCSSDeclaration(args);
+            return this.compileCSSDeclaration(`after, ${args}`);
         case ':matches-css-before':
-            return this.compileCSSDeclaration(args);
+            return this.compileCSSDeclaration(`before, ${args}`);
         case ':matches-media':
             return this.compileMediaQuery(args);
         case ':matches-path':