fix: work with rc-form

package.json

@@ -1,6 +1,6 @@
 {
   "name": "rc-slider",
-  "version": "3.3.1",
+  "version": "3.3.2",
   "description": "slider ui component for react",
   "keywords": [
     "react",

src/Slider.jsx

@@ -34,7 +34,7 @@ class Slider extends React.Component {
     const {range, min, max} = props;
     const initialValue = range ? [min, min] : min;
     const defaultValue = ('defaultValue' in props ? props.defaultValue : initialValue);
-    const value = ('value' in props ? props.value : defaultValue);
+    const value = (props.value !== undefined ? props.value : defaultValue);
 
     let upperBound;
     let lowerBound;
@@ -85,7 +85,7 @@ class Slider extends React.Component {
         this.props.onChange([nextLowerBound, nextUpperBound]);
       }
     } else {
-      const value = 'value' in nextProps ? nextProps.value : upperBound;
+      const value = nextProps.value !== undefined ? nextProps.value : upperBound;
       const nextValue = this.trimAlignValue(value, nextProps);
       if (nextValue === upperBound && lowerBound === nextProps.min) return;