Add tests

tests/cases/conformance/es6/restParameters/readonlyRestParameters.ts

@@ -0,0 +1,29 @@
+// @strict: true
+// @declaration: true
+
+function f0(a: string, b: string) {
+    f0(a, b);
+    f1(a, b);
+    f2(a, b);
+}
+
+function f1(...args: readonly string[]) {
+    f0(...args);  // Error
+    f1('abc', 'def');
+    f1('abc', ...args);
+    f1(...args);
+}
+
+function f2(...args: readonly [string, string]) {
+    f0(...args);
+    f1('abc', 'def');
+    f1('abc', ...args);
+    f1(...args);
+    f2('abc', 'def');
+    f2('abc', ...args);  // Error
+    f2(...args);
+}
+
+function f4(...args: readonly string[]) {
+    args[0] = 'abc';  // Error
+}