Add regression test for #19395

Thanks to @mjbvz for finding it and @sandersn for reducing it.

tests/cases/fourslash/extract-method27.ts

@@ -0,0 +1,34 @@
+/// <reference path='fourslash.ts' />
+
+// Repro https://github.com/Microsoft/TypeScript/issues/19395
+
+// @Filename: test.ts
+//// export const b = 2;
+//// interface Interface { }
+////
+//// async function handle(i: Interface) {
+////     /*a*/const x = 3, y = i;/*b*/
+//// }
+// @Filename: library.d.ts
+//// export as namespace NS;
+//// export const a = 1;
+
+
+goTo.select('a', 'b')
+edit.applyRefactor({
+    refactorName: "Extract Symbol",
+    actionName: "function_scope_1",
+    actionDescription: "Extract to function in module scope",
+    newContent:
+`export const b = 2;
+interface Interface { }
+
+async function handle(i: Interface) {
+    /*RENAME*/newFunction(i);
+}
+
+function newFunction(i: Interface) {
+    const x = 3, y = i;
+}
+`
+});