Add UrlCodeHints for poster-attribute

src/extensions/default/UrlCodeHints/data.json

@@ -1,6 +1,7 @@
 {
     "htmlAttrs": {
         "href":         { "attribOption": [] },
+        "poster":       { "attribOption": [] },
         "src":          { "attribOption": [] }
     }
 }

src/extensions/default/UrlCodeHints/testfiles/test.html

@@ -22,5 +22,6 @@
   <a href='../'>Page relative: up 1 folder</a>
   <a href='/'>Site-root relative: root folder</a>
   <a href='test2.html'>Results</a>
+  <video poster=''>Results</video>
 </body>
 </html>

src/extensions/default/UrlCodeHints/unittests.js

@@ -166,6 +166,18 @@ define(function (require, exports, module) {
                     verifyUrlHints(hintsObj.hints, testfilesDirHints);
                 });
             });
+
+            it("should hint for poster attribute", function () {
+                runs(function () {
+                    testEditor.setCursorPos({ line: 24, ch: 17 });
+                    hintsObj = null;
+                    expectAsyncHints(UrlCodeHints.hintProvider);
+                });
+
+                runs(function () {
+                    verifyUrlHints(hintsObj.hints, testfilesDirHints);
+                });
+            });
 
             it("should not hint for type attribute", function () {
                 runs(function () {