fix: Clear fix (#36)

* add clear

* fix test case

Author: zombieJ

src/Picker.tsx

@@ -405,6 +405,10 @@ function InnerPicker<DateType>(props: PickerProps<DateType>) {
         onMouseDown={e => {
           e.preventDefault();
           e.stopPropagation();
+        }}
+        onMouseUp={e => {
+          e.preventDefault();
+          e.stopPropagation();
           triggerChange(null);
           triggerOpen(false, true);
         }}

src/RangePicker.tsx

@@ -907,6 +907,10 @@ function InnerRangePicker<DateType>(props: RangePickerProps<DateType>) {
         onMouseDown={e => {
           e.preventDefault();
           e.stopPropagation();
+        }}
+        onMouseUp={e => {
+          e.preventDefault();
+          e.stopPropagation();
           let values = mergedValue;
 
           if (!mergedDisabled[0]) {

tests/setup.js

@@ -74,6 +74,7 @@ Object.assign(Enzyme.ReactWrapper.prototype, {
   },
   clearValue() {
     this.find('.rc-picker-clear-btn').simulate('mouseDown');
+    this.find('.rc-picker-clear-btn').simulate('mouseUp');
   },
   keyDown(which, info = {}, index = 0) {
     this.find('input')