Added test for lossless WebP images

feature-detects/img-webp-lossless.js

@@ -0,0 +1,20 @@
+// code.google.com/speed/webp/
+// tests for lossless webp support, as detailed in https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification
+// by @amandeep - based off of the img-webp-test
+
+// This test is asynchronous. Watch out.
+
+(function(){
+
+  var image = new Image();
+
+  image.onerror = function() {
+      Modernizr.addTest('webp-lossless', false);
+  };  
+  image.onload = function() {
+      Modernizr.addTest('webp-lossless', function() { return image.width == 1; });
+  };
+
+  image.src = 'data:image/webp;base64,UklGRhoAAABXRUJQVlA4TA0AAAAvAAAAEAcQERGIiP4HAA==';
+
+}());