Merge pull request #16 from abarth/no-repaint

Remove spurious repaints in core-list

Author: kevinpschaaf

core-list.css

@@ -1,9 +1,6 @@
 :host {
   display: block;
   overflow: auto;
-  /*-webkit-overflow-scrolling: touch;
-  -webkit-transform: translateZ(0);
-  transform: translateZ(0);*/
 }
 
 .core-list-viewport > * {
@@ -17,4 +14,11 @@
 
 .core-list-viewport.horizontal > * {
   display: inline-block;
-}
+}
+
+/* Setting will-change: transform on the #viewport makes the viewport a
+   stacking context, which causes all the composited layers inside the
+   viewport to actually be stacked underneath the viewport. */
+#viewport {
+  will-change: transform;
+}

core-list.html

@@ -387,12 +387,12 @@
 
   // determine proper transform mechanizm
   if (document.documentElement.style.transform !== undefined) {
-    function setTransform(element, string, value) {
+    var setTransform = function(element, string, value) {
       element.style.transform = string;
       element._transformValue = value;
     }
   } else {
-    function setTransform(element, string, value) {
+    var setTransform = function(element, string, value) {
       element.style.webkitTransform = string;
       element._transformValue = value;
     }