Serveral issues on Opera browser

[gartz]

I was trying to debug and help to find why the plataform isn't working on Opera browser, but I couldn't looks like somewhere when wrapping methods, it pass a undefined value, then it throw exception because there isn't a treatment for undefined value, it try to consider the undefined as an Object, and Opera don't allow to parse it.

The bug begins in ShadowDOM, file wrapper.js in this method:

 /**
   * Forwards existing methods on the native object to the wrapper methods.
   * This does not wrap any of the arguments or the return value since the
   * wrapper implementation already takes care of that.
   * @param {Array.<Function>} constructors
   * @parem {Array.<string>} names
   */
  function forwardMethodsToWrapper(constructors, names) {
    constructors.forEach(function(constructor) {
      names.forEach(function(name) {
        constructor.prototype[name] = function() {
          var w = wrapIfNeeded(this);
          return w[name].apply(w, arguments);
        };
      });
    });
  }

[gartz]

Ok, I'm working to fix the issues, so I have made a pull request in the HTMLImports project that add support to matchesSelector for Opera12.

googlearchive/HTMLImports#48

Another thing, to make HTMLImports work in Opera 12 you will need a shim for the requestFrameAnimation, that doesn't have native support on Opera 12:

(function () {
    var lastTime = 0;
    var vendors = ['ms', 'moz', 'webkit', 'o'];
    for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
        window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame'];
        window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame']
                                   || window[vendors[x]+'CancelRequestAnimationFrame'];
    }

    if (!window.requestAnimationFrame)
        window.requestAnimationFrame = function(callback, element) {
            var currTime = new Date().getTime();
            var timeToCall = Math.max(0, 16 - (currTime - lastTime));
            var id = window.setTimeout(function() { callback(currTime + timeToCall); },
              timeToCall);
            lastTime = currTime + timeToCall;
            return id;
        };

    if (!window.cancelAnimationFrame)
        window.cancelAnimationFrame = function(id) {
            clearTimeout(id);
        };
})();

Soon I found other needs for Opera 12 support I will add here.

[gartz]

Another fix to add shadowDOM support to Opera 12: googlearchive/ShadowDOM#373

[arv]

Sorry. Wont Fix.

Opera 12 is discontinued and will never get native support for web components. Our goal is to get rid of these polyfills eventually and a discontinued browser is not going to help here.