fix(tooltips): remove Object.values usage for IE11 support

[austingreendev]

Closes #121. Thanks @SabaRathnamK!

Description

We were using Object.values() without a babel transform for IE11. This forces consumers to include the applicable polyfills, which isn't something we should force onto people.

This PR:

• Refactors the Object.values() code with IE11 compatible logic

Unrelated:

• Removed the babel-plugin prefix from babel-plugin-styled-components as it's not needed

Detail

I tested this locally in create-react-app (no polyfills) in IE11 and it's no longer failing!

Checklist

• 👌 design updates are Garden Designer approved (add the
  designer as a reviewer)
• 💅 view component styling is based on a Garden CSS
  component
• 🌐 Styleguidist demo is up-to-date (yarn start)
• ⬅️ renders as expected with reversed (RTL) direction
• 💂‍♂️ includes new unit and snapshot tests
• 📒 any new files are included in the packages src/index.js export
• 📝 tested in Chrome, Firefox, Safari, Edge, and IE11

[coveralls]

Coverage decreased (-0.03%) to 96.092% when pulling 1630c84 on agreen/ie11-object-values into 376b4bb on master.

[austingreendev]

@jzempel this is still 100% coverage, just more lines in the solution. Could we modify coveralls as mentioned in #129?