Adding no-filter rules

src/rules/no-filter.js

@@ -0,0 +1,28 @@
+/*
+ * Rule: Filter is experimental and may have unexpected behavior
+ */
+
+CSSLint.addRule({
+
+    // rule information
+    id: "no-filter",
+    name: "Disallow filter",
+    desc: "Filter does not have a stable specification and should not be used",
+    url: "https://github.com/hrobertking/csslint/wiki/Disallow-filter",
+    browsers: "All",
+
+    // initialization
+    init: function(parser, reporter) {
+        "use strict";
+        var rule = this;
+
+        // report a use of 'filter'
+        parser.addListener("property", function(event) {
+            if (event.property.toString().toLowerCase() === "filter") {
+                reporter.report("The filter property is not allowed", event.line, event.col, rule);
+            }
+        });
+
+    }
+
+});

tests/rules/no-filter.js

@@ -0,0 +1,18 @@
+(function() {
+    "use strict";
+
+    var Assert = YUITest.Assert;
+
+    YUITest.TestRunner.add(new YUITest.TestCase({
+        name: "Unstable filter property",
+
+        "Use of 'filter' should result in a warning": function() {
+            var result = CSSLint.verify("h1 { filter: alpha(opacity=40); }", { "no-filter": 1 });
+
+            Assert.areEqual(1, result.messages.length);
+            Assert.areEqual("warning", result.messages[0].type);
+            Assert.areEqual("The filter property is not allowed", result.messages[0].message);
+        }
+    }));
+})();
+