Prevent frame scroll on the first component drag. Fixes #3134

src/canvas/view/FrameView.js

@@ -1,5 +1,5 @@
 import Backbone from 'backbone';
-import { bindAll, isString, debounce } from 'underscore';
+import { bindAll, isString, debounce, isUndefined } from 'underscore';
 import CssRulesView from 'css_composer/view/CssRulesView';
 import ComponentView from 'dom_components/view/ComponentView';
 import {
@@ -162,11 +162,12 @@ export default Backbone.View.extend({
 
   autoscroll() {
     if (this.dragging) {
+      const { lastClientY } = this;
       const canvas = this.em.get('Canvas');
       const win = this.getWindow();
       const body = this.getBody();
       const actualTop = body.scrollTop;
-      const clientY = this.lastClientY || 0;
+      const clientY = lastClientY || 0;
       const limitTop = canvas.getConfig().autoscrollLimit;
       const limitBottom = this.getRect().height - limitTop;
       let nextTop = actualTop;
@@ -180,6 +181,7 @@ export default Backbone.View.extend({
       }
 
       if (
+        !isUndefined(lastClientY) && // Fixes #3134
         nextTop !== actualTop &&
         nextTop > 0 &&
         nextTop < this.lastMaxHeight