remove single item from top: Padding cache logic

Author: dhilt

src/modules/adapter.js

@@ -163,7 +163,7 @@ class Adapter {
     }
     // remove single item
     if(!newItems.length) {
-      this.viewport.removeCacheItem(index, true);
+      this.viewport.removeCacheItem(index, index === this.buffer.minIndex);
     }
   }
 

src/modules/padding.js

@@ -15,9 +15,9 @@ class CacheProto {
     this.sort((a, b) => ((a.index < b.index) ? -1 : ((a.index > b.index) ? 1 : 0)));
   }
 
-  remove(argument) {
+  remove(argument, _isTop) {
     const index = argument % 1 === 0 ? argument : argument.scope.$index;
-    const isTop = argument % 1 === 0 ? false : argument._op === 'isTop';
+    const isTop = argument % 1 === 0 ? _isTop : argument._op === 'isTop';
     for (let i = this.length - 1; i >= 0; i--) {
       if (this[i].index === index) {
         this.splice(i, 1);

src/modules/viewport.js

@@ -182,9 +182,9 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
       bottomPadding.cache.clear();
     },
 
-    removeCacheItem(item) {
-      topPadding.cache.remove(item);
-      bottomPadding.cache.remove(item);
+    removeCacheItem(item, isTop) {
+      topPadding.cache.remove(item, isTop);
+      bottomPadding.cache.remove(item, isTop);
     },
 
     removeItem(item) {