MatSelect: dropdown arrow renders as rectangle in high-contrast mode

[ankz2390]

Bug, feature request, or proposal:
Bug

What is the expected behavior?
Dropdown arrow should be visible on windows HC mode

What is the current behavior?
Dropdown icon not visible. Replaced with a small box

What are the steps to reproduce?
Activate windows HC mode using accessibility menu,

What is the use-case or motivation for changing an existing behavior?
Catering for accessibility for disabilities requiring high contrast modes

Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Edge