Add test for regression

Author: andrewbranch

tests/cases/conformance/classes/propertyMemberDeclarations/instanceMemberInitialization.ts

@@ -5,4 +5,10 @@ class C {
 var c = new C();
 c.x = 3;
 var c2 = new C();
-var r = c.x === c2.x;
+var r = c.x === c2.x;
+
+// #31792
+export class MyMap<K, V> {
+	constructor(private readonly Map_: typeof Map = Map) {}
+	private readonly store = new this.Map_<K, V>();
+}