fix background-imgae none 的编译error

packages/webpack-plugin/lib/platform/style/wx/index.js

@@ -315,7 +315,7 @@ module.exports = function getSpec ({ warn, error }) {
     switch (prop) {
       case bgPropMap.image: {
         // background-image 支持背景图/渐变/css var
-        if (cssVariableExp.test(value) || urlExp.test(value) || linearExp.test(value)) {
+        if (cssVariableExp.test(value) || urlExp.test(value) || linearExp.test(value) || value === 'none') {
           return { prop, value }
         } else {
           error(`Value of ${prop} in ${selector} selector only support value <url()> or <linear-gradient()>, received ${value}, please check again!`)
@@ -359,6 +359,13 @@ module.exports = function getSpec ({ warn, error }) {
           error(`Property [${bgPropMap.all}] in ${selector} is abbreviated property and does not support CSS var`)
           return false
         }
+        // background: none
+        if (value === 'none') {
+          return [
+            { prop: bgPropMap.image, value },
+            { prop: bgPropMap.color, value: 'transparent' }
+          ]
+        }
         const bgMap = []
         const values = parseValues(value)
         values.forEach(item => {

packages/webpack-plugin/lib/runtime/components/react/mpx-view.tsx

@@ -501,7 +501,7 @@ function parseBgImage (text: string): {
   type?: 'image' | 'linear'
   src?: string
 } {
-  if (!text) return {}
+  if (!text || text === 'none') return {}
 
   const src = parseUrl(text)
   if (src) return { src, type: 'image' }