avoid using native implementation by default when document.webkitRegi…

…ster is available. This is an outdated native implementation that is no longer spec compliant.

src/CustomElements.js

@@ -25,14 +25,11 @@ var flags = scope.flags;
 
 // native document.register?
 
-var hasNative = Boolean(document.webkitRegister || document.register);
+var hasNative = Boolean(document.register);
 var useNative = !flags.register && hasNative;
 
 if (useNative) {
 
-  // normalize
-  document.register = document.register || document.webkitRegister;
-
   // stub
   var nop = function() {};