Work around Tizen reporting on persistent licenses

This works around Tizen 3.0's misreporting of its support for
persistent licenses, which prevents us from running persistent
license tests on that platform.

There is still one more failing test on this platform.

Issue #894

Change-Id: I81ebb80a831c753e3af4851efcbd7e97211e6890

lib/media/drm_engine.js

@@ -1371,6 +1371,15 @@ shaka.media.DrmEngine.probeSupport = function() {
           var sessionTypes = access.getConfiguration().sessionTypes;
           var persistentState = sessionTypes ?
               sessionTypes.indexOf('persistent-license') >= 0 : false;
+
+          // Tizen 3.0 doesn't support persistent licenses, but reports that it
+          // does.  It doesn't fail until you call update() with a license
+          // response, which is way too late.
+          // This is a work-around for #894.
+          if (navigator.userAgent.indexOf('Tizen 3') >= 0) {
+            persistentState = false;
+          }
+
           support[keySystem] = {persistentState: persistentState};
           return access.createMediaKeys();
         }).catch(function() {