fix(compiler): make projectReferences work with isolatedModules: true

e2e/__cases__/diagnostics/warn/main.spec.ts

@@ -0,0 +1,7 @@
+import { foo, Thing } from './main';
+
+export const thing: Thing = { a: 1 };
+
+test('foo is 42', () => {
+  expect(foo).toBe(42);
+});

e2e/__cases__/diagnostics/warn/main.ts

@@ -0,0 +1,2 @@
+export const foo = 42
+export type Thing = { a: number, b: number }