Test:property access respects readonly index signature

tests/baselines/reference/propertyAccessOfReadonlyIndexSignature.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/compiler/propertyAccessOfReadonlyIndexSignature.ts(6,1): error TS2542: Index signature in type 'Test' only permits reading.
+
+
+==== tests/cases/compiler/propertyAccessOfReadonlyIndexSignature.ts (1 errors) ====
+    interface Test {
+        readonly [key: string]: string;
+    }
+    
+    declare var a: Test;
+    a.foo = 'baz';
+    ~~~~~
+!!! error TS2542: Index signature in type 'Test' only permits reading.
+    

tests/baselines/reference/propertyAccessOfReadonlyIndexSignature.js

@@ -0,0 +1,11 @@
+//// [propertyAccessOfReadonlyIndexSignature.ts]
+interface Test {
+    readonly [key: string]: string;
+}
+
+declare var a: Test;
+a.foo = 'baz';
+
+
+//// [propertyAccessOfReadonlyIndexSignature.js]
+a.foo = 'baz';

tests/cases/compiler/propertyAccessOfReadonlyIndexSignature.ts

@@ -0,0 +1,6 @@
+interface Test {
+    readonly [key: string]: string;
+}
+
+declare var a: Test;
+a.foo = 'baz';