[search] polyfill search component to catch errors

[katydecorah]

While reviewing Sentry errors, I noticed that the search component is throwing errors in older browser versions like Firefox 44.

• Adding babel's poyfill to the search component fixes this issue with older browsers versions (just not IE11 because it's out of scope for the search library).
• Ref: https://sentry.io/organizations/mapboxcom/issues/1131166287/?referrer=slack

I built this PR locally and tested on /geographic-analytics:

• IE 11 works
  

• Firefox 44 works (The search component works , too. I'm not concerned about that weird icon positioning since it doesn't appear in the latest versions of Firefox.)
  

You can test this PR by:

1. npm install
2. npm run build
3. Opening another repo to test locally, like geographic-analytics, and replacing the dr-ui version number in package.json with the path to your local dr-ui repo: "@mapbox/dr-ui": "file:/Users/katydecorah/Documents/GitHub/dr-ui/pkg",
4. run npm install (you may need to delete node_modules first) on the tester repo and then npm start
5. open browserstack with Firefox 44 to confirm the site loads locally.

[colleenmcginnis]

@katydecorah I tested this in /ios-sdk and it works as expected on npm start. I get the following error when running npm run build:

../dr-ui/pkg/back-to-top-button/index.js
Module build failed: ReferenceError: Unknown plugin "babel-plugin-transform-react-remove-prop-types" specified in "base" at 4, attempted to resolve relative to "/path/to/folder/dr-ui/pkg/back-to-top-button"
    at Array.map (<anonymous>)

[katydecorah]

@colleenmcginnis looks like adding babel-plugin-transform-react-remove-prop-types here as a dependency fixed that error. I'm not exactly sure why yet. My first guess is that it's a peer dependency for one of the two packages also installed in this PR.

[colleenmcginnis]

I retested this with the most recent changes and the build works as expected!