test: fix objectSpread test

In babel 7.5.x releases, something has changed in the objec spread
plugin, the helper now may be inlined rather than imported, so we now
only check for the invocation in the test.

Author: haoqunjiang

packages/@vue/babel-preset-app/__tests__/babel-preset.spec.js

@@ -86,7 +86,7 @@ test('object spread', () => {
   const { code } = babel.transformSync(`
     const a = { ...b }
   `.trim(), defaultOptions)
-  expect(code).toMatch(`import _objectSpread from`)
+  // expect(code).toMatch(`import _objectSpread from`)
   expect(code).toMatch(`var a = _objectSpread({}, b)`)
 })