Add tests for decorators and declaration emit from error free source

Author: ahejlsberg

tests/cases/conformance/types/tuple/readonlyArraysAndTuples2.ts

@@ -0,0 +1,23 @@
+// @strict: true
+// @declaration: true
+// @emitDecoratorMetadata: true
+// @experimentalDecorators: true
+
+type T10 = string[];
+type T11 = Array<string>;
+type T12 = readonly string[];
+type T13 = ReadonlyArray<string>;
+
+type T20 = [number, number];
+type T21 = readonly [number, number];
+
+declare function f1(ma: string[], ra: readonly string[], mt: [string, string], rt: readonly [string, string]): readonly [string, string];
+
+declare const someDec: any;
+
+class A {
+  @someDec
+  j: readonly string[] = [];
+  @someDec
+  k: readonly [string, number] = ['foo', 42];
+}