fix($compile): Bump track src from URL to RESOURCE_URL.

Track files might contain CSS, and haven't been around for long. Keeping the
high security context as a precaution is justified.

Author: rjamet

src/ng/compile.js

@@ -3152,9 +3152,10 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
       }
       var tag = nodeName_(node);
       // All tags with src attributes require a RESOURCE_URL value, except for
-      // img and various html5 media tags.
+      // img and various html5 media tags. Note that track src allows files
+      // containing CSS, so leave that to RESOURCE_URL level.
       if (attrNormalizedName === 'src' || attrNormalizedName === 'ngSrc') {
-        if (['img', 'video', 'audio', 'track'].indexOf(tag) === -1) {
+        if (['img', 'video', 'audio'].indexOf(tag) === -1) {
           return $sce.RESOURCE_URL;
         }
       // maction[xlink:href] can source SVG.  It's not limited to <maction>.