fix: handle shallowMount on components with v-if and scoped slots

[xanf]

vuejs/vue@d9b27a9 introduced a new $key property, stored inside scopedSlots to solve issues when component with scoped-slots is rendered inside v-if

As for now VTU crashes when trying to shallowRender such component, since $key is not filtered out when VTU tries to invoke each slot. This MR fixes this behavior

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the dev branch.
• [-] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue-test-utils/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

[lmiller1990]

Thanks! I will release this within 1h.

Trust the GitLab team to find the smallest bugs. Maybe before each release of Vue and VTU we should run them against the GitLab test suite :D

[lmiller1990]

It's out here: https://github.com/vuejs/vue-test-utils/releases/tag/v1.0.5

[xanf]

@lmiller1990 thank you for you trust :) I'm migrating our codebase from beta.30 to 1.0.5, trying also to remove all possible deprecation warnings - some are quite painful :(

[lmiller1990]

@xanf if you feel the deprecations are inappropriate can you please make an issue (for the ones you don't agree with).

I thought about this a little more lately and I think we were too aggressive with the them. I think exists and possibly visible should come back. What do you think?