Eslint prefer-object-spread (#9466)

* The rule.

* The result

superset-frontend/src/explore/components/ControlPanelsContainer.jsx

@@ -75,11 +75,10 @@ class ControlPanelsContainer extends React.Component {
     }
     // Applying mapStateToProps if needed
     if (mapF) {
-      return Object.assign(
-        {},
-        control,
-        mapF(this.props.exploreState, control, this.props.actions),
-      );
+      return {
+        ...control,
+        ...mapF(this.props.exploreState, control, this.props.actions),
+      };
     }
     return control;
   }

superset-frontend/src/explore/components/ExploreViewContainer.jsx

@@ -418,13 +418,12 @@ function mapStateToProps(state) {
 }
 
 function mapDispatchToProps(dispatch) {
-  const actions = Object.assign(
-    {},
-    exploreActions,
-    saveModalActions,
-    chartActions,
-    logActions,
-  );
+  const actions = {
+    ...exploreActions,
+    ...saveModalActions,
+    ...chartActions,
+    ...logActions,
+  };
   return {
     actions: bindActionCreators(actions, dispatch),
   };

superset-frontend/src/explore/components/controls/ColorPickerControl.jsx

@@ -88,9 +88,10 @@ export default class ColorPickerControl extends React.Component {
   }
   render() {
     const c = this.props.value || { r: 0, g: 0, b: 0, a: 0 };
-    const colStyle = Object.assign({}, styles.color, {
+    const colStyle = {
+      ...styles.color,
       background: `rgba(${c.r}, ${c.g}, ${c.b}, ${c.a})`,
-    });
+    };
     return (
       <div>
         <ControlHeader {...this.props} />