update: reset 'start' value in 'beforeMount' stage.

Author: KyLeoHC

dist/vue-scroll-list.js

@@ -106,6 +106,7 @@ var component = {
         var remains = this.remain;
         var delta = this.$options.delta;
 
+        delta.start = 0;
         delta.end = remains + delta.reserve - 1;
         delta.keeps = remains + delta.reserve;
     },

index.js

@@ -100,6 +100,7 @@ let component = {
         let remains = this.remain;
         let delta = this.$options.delta;
 
+        delta.start = 0;
         delta.end = remains + delta.reserve - 1;
         delta.keeps = remains + delta.reserve;
     },