message: fix(wxa): clean cached ctx for different environments
diff: @@ -40,6 +40,11 @@ var nativeReduce = arrayProto.reduce;
  var methods = {};
  export function $override(name, fn) {
  + // Clear ctx instance for different environment
  + if (name === 'createCanvas') {
  + _ctx = null;
  + }
  +
  methods[name] = fn;
  }
  