Initialize the `$refs` value

@inner
function initRefs() {
    this.$refs = {};

    let refs = this.$rawRefData;
    if (typeof refs === 'function') {
        refs = refs();
    }

    if (!refs) {
        return;
    }

    let result = {};
    const self = this;
    Object.keys(refs).forEach(id => {
        result[id] = {
            get() {
                let value = refs[id];
                return queryRefInstance.call(self, value);
            },
            enumerable: true
        };
    });

    Object.defineProperties(this.$refs, result);
}