Parser: Support nested media queries

Description https://www.w3.org/TR/css3-conditional/#processing

Fixes #118

Author: nschonni

src/css/Parser.js

@@ -527,6 +527,8 @@ Parser.prototype = function() {
                         this._document();
                     } else if (tokenStream.peek() === Tokens.SUPPORTS_SYM) {
                         this._supports();
+                    } else if (tokenStream.peek() === Tokens.MEDIA_SYM) {
+                        this._media();
                     } else if (!this._ruleset()) {
                         break;
                     }

tests/css/Parser.js

@@ -1702,6 +1702,18 @@ var YUITest = require("yuitest"),
             Assert.isTrue(valid);
         },
 
+        testMediaWithNestedMedia: function() {
+            var parser = new Parser({ strict: true });
+            var valid = true;
+
+            parser.addListener("error", function() {
+                valid = false;
+            });
+
+            parser.parse("@media print { #navigation { display: none } @media (max-width: 12cm) { .note { float: none } } }");
+            Assert.isTrue(valid);
+        },
+
         testViewport: function() {
             var parser = new Parser({ strict: true });
             var valid = true;