MD-Settings - Update iron-list to fix scroll issue.

third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js

 (function() {
 
   var IOS = navigator.userAgent.match(/iP(?:hone|ad;(?: U;)? CPU) OS (\d+)/);
   var IOS_TOUCH_SCROLLING = IOS && IOS[1] >= 8;
   var DEFAULT_PHYSICAL_COUNT = 3;
   var HIDDEN_Y = '-10000px';
   var ITEM_WIDTH = 0;
   var ITEM_HEIGHT = 1;
   var SECRET_TABINDEX = -100;
 
@@ skipping 540 matching lines @@
       var scrollTop = Math.max(0, Math.min(this._maxScrollTop, this._scrollTop));
       var delta = scrollTop - this._scrollPosition;
       var isScrollingDown = delta >= 0;
       // Track the current scroll position.
       this._scrollPosition = scrollTop;
       // Clear indexes.
       this._firstVisibleIndexVal = null;
       this._lastVisibleIndexVal = null;
 
       // Random access.
-      if (Math.abs(delta) > this._physicalSize) {
+      if (Math.abs(delta) > this._physicalSize && this._physicalSize > 0) {
         delta = delta - this._scrollOffset;
         var idxAdjustment = Math.round(delta / this._physicalAverage) * this._itemsPerRow;
-        this._physicalTop = this._physicalTop + delta;
         this._virtualStart = this._virtualStart + idxAdjustment;
         this._physicalStart = this._physicalStart + idxAdjustment;
+        // Estimate new physical offset.
+        this._physicalTop = Math.floor(this._virtualStart / this._itemsPerRow) * this._physicalAverage;
         this._update();
       } else {
         var reusables = this._getReusables(isScrollingDown);
         if (isScrollingDown) {
           this._physicalTop = reusables.physicalTop;
           this._virtualStart = this._virtualStart + reusables.indexes.length;
           this._physicalStart = this._physicalStart + reusables.indexes.length;
         } else {
           this._virtualStart = this._virtualStart - reusables.indexes.length;
           this._physicalStart = this._physicalStart - reusables.indexes.length;
@@ skipping 959 matching lines @@
       this._assignModels();
       // Get the new physical index for the focused index.
       pidx = this._getPhysicalIndex(fidx);
 
       var onScreenItem = this._physicalItems[pidx];
       if (!onScreenItem) {
         return;
       }
       var onScreenInstance = onScreenItem._templateInstance;
       var offScreenInstance = this._offscreenFocusedItem._templateInstance;
-      // Restores the physical item only when it has the same model 
+      // Restores the physical item only when it has the same model
       // as the offscreen one. Use key for comparison since users can set
       // a new item via set('items.idx').
       if (onScreenInstance.__key__ === offScreenInstance.__key__) {
         // Flip the focus backfill.
         this._focusBackfillItem = onScreenItem;
         onScreenInstance.tabIndex = -1;
         // Restore the focused physical item.
         this._physicalItems[pidx] = this._offscreenFocusedItem;
         // Hide the physical item that backfills.
         this.translate3d(0, HIDDEN_Y, 0, this._focusBackfillItem);
       } else {
+        this._removeFocusedItem();
         this._focusBackfillItem = null;
       }
       this._offscreenFocusedItem = null;
     },
 
     _didFocus: function(e) {
       var targetModel = this.modelForElement(e.target);
       var focusedModel = this._focusedItem ? this._focusedItem._templateInstance : null;
       var hasOffscreenFocusedItem = this._offscreenFocusedItem !== null;
       var fidx = this._focusedIndex;
@@ skipping 31 matching lines @@
       this._focusPhysicalItem(this._focusedIndex + 1);
     },
 
     _didEnter: function(e) {
       this._focusPhysicalItem(this._focusedIndex);
       this._selectionHandler(e.detail.keyboardEvent);
     }
   });
 
 })();