This commit removes polyfills that were needed to run tests on IE 9 and IE 10.
BREAKING CHANGE:
In v10, IE 9, 10, and IE mobile support was deprecated. In v11, Angular framework removes IE 9,
10, and IE mobile support completely.
Supporting outdated browsers like these increases bundle size, code complexity, and test load,
and also requires time and effort that could be spent on improvements to the framework.
For example, fixing issues can be more difficult, as a straightforward fix for modern browsers
could break old ones that have quirks due to not receiving updates from vendors.
PR Close#38931
The shims_for_IE.js file contains vendor code that predates the third_party
directory. This file is currently used for internal karma testing setup. This
change corrects this by moving the shims_for_IE file to //third_part/
PR Close#37624