Add tests and baseline

tests/baselines/reference/classExtendsNull.errors.txt

@@ -0,0 +1,21 @@
+tests/cases/compiler/classExtendsNull.ts(2,5): error TS17005: A constructor can not contain super call when a class extends null
+
+
+==== tests/cases/compiler/classExtendsNull.ts (1 errors) ====
+    class C extends null {
+        constructor() {
+        ~~~~~~~~~~~~~~~
+            super();
+    ~~~~~~~~~~~~~~~~
+            return Object.create(null);
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+        }
+    ~~~~~
+!!! error TS17005: A constructor can not contain super call when a class extends null
+    }
+    
+    class D extends null {
+        constructor() {
+            return Object.create(null);
+        }
+    }

tests/baselines/reference/classExtendsNull.js

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+//// [classExtendsNull.ts]
+class C extends null {
+    constructor() {
+        super();
+        return Object.create(null);
+    }
+}
+
+class D extends null {
+    constructor() {
+        return Object.create(null);
+    }
+}
+
+//// [classExtendsNull.js]
+var __extends = (this && this.__extends) || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+};
+var C = (function (_super) {
+    __extends(C, _super);
+    function C() {
+        _super.call(this);
+        return Object.create(null);
+    }
+    return C;
+})(null);
+var D = (function (_super) {
+    __extends(D, _super);
+    function D() {
+        return Object.create(null);
+    }
+    return D;
+})(null);

tests/cases/compiler/classExtendsNull.ts

@@ -0,0 +1,12 @@
+class C extends null {
+    constructor() {
+        super();
+        return Object.create(null);
+    }
+}
+
+class D extends null {
+    constructor() {
+        return Object.create(null);
+    }
+}