Added a condition to check if properties in the Navigation timing API are available - Fixes #149 and #157

src/renderers/dom.js

@@ -40,7 +40,7 @@ Physics.renderer('dom', function( proto ){
                 }
             }
 
-            if (name in tmpdiv.style){
+            if (prop in tmpdiv.style){
                 return thePrefix[prop] = prop;
             }
 

src/util/ticker.js

@@ -14,7 +14,7 @@
 
     function now(){
         // http://updates.html5rocks.com/2012/05/requestAnimationFrame-API-now-with-sub-millisecond-precision
-        return (perf && perf.now) ?
+        return (perf && perf.now && perf.timing && perf.timing.navigationStart) ?
             (perf.now() + perf.timing.navigationStart) :
             Date.now();
     }