Fix overwritten warn in Vue 2.1.8, fixed #2040 (#2047)

* Fix overwritten warn in Vue 2.1.8, fixed #2040

* Fix dropdown-menu

* Fix placement again

* fix test

packages/date-picker/src/picker.vue

@@ -202,7 +202,6 @@ export default {
       default: 'left'
     },
     value: {},
-    haveTrigger: {},
     pickerOptions: {}
   },
 

packages/dropdown/src/dropdown-menu.vue

@@ -26,9 +26,9 @@
       this.referenceElm = this.$parent.$el;
     },
 
-    computed: {
+    watch: {
-      placement() {
+      '$parent.menuAlign'(val) {
-        return `bottom-${this.$parent.menuAlign}`;
+        this.currentPlacement = `bottom-${val}`;
       }
     }
   };

packages/rate/src/main.vue

@@ -33,7 +33,6 @@
       return {
         classMap: {},
         colorMap: {},
-        classes: null,
         pointerAtLeftHalf: false,
         currentValue: this.value,
         hoverIndex: -1

src/utils/vue-popper.js

@@ -46,7 +46,8 @@ export default {
 
   data() {
     return {
-      showPopper: false
+      showPopper: false,
+      currentPlacement: ''
     };
   },
 
@@ -68,7 +69,8 @@ export default {
   methods: {
     createPopper() {
       if (this.$isServer) return;
-      if (!/^(top|bottom|left|right)(-start|-end)?$/g.test(this.placement)) {
+      this.currentPlacement = this.currentPlacement || this.placement;
+      if (!/^(top|bottom|left|right)(-start|-end)?$/g.test(this.currentPlacement)) {
         return;
       }
 
@@ -88,7 +90,7 @@ export default {
         this.popperJS.destroy();
       }
 
-      options.placement = this.placement;
+      options.placement = this.currentPlacement;
       options.offset = this.offset;
       this.popperJS = new PopperJS(reference, popper, options);
       this.popperJS.onCreate(_ => {