test: remove unecessary id in test case

yyx990803 · yyx990803 · commit afa108238f95 · 2017-07-11T16:55:14.000+08:00
diff --git a/test/unit/features/directives/on.spec.js b/test/unit/features/directives/on.spec.js
@@ -661,7 +661,6 @@ describe('Directive v-on', () => {
       el,
       template: `
         <foo-button
-          id="foo"
           @click="click"
           @mousedown="mousedown"
           @mouseup.native="mouseup">
