Add test case for narrowed const in object literal and class expression method

Author: sheetalkamat

tests/baselines/reference/narrowedConstInMethod.errors.txt

@@ -0,0 +1,27 @@
+tests/cases/compiler/narrowedConstInMethod.ts(6,28): error TS2531: Object is possibly 'null'.
+tests/cases/compiler/narrowedConstInMethod.ts(15,28): error TS2531: Object is possibly 'null'.
+
+
+==== tests/cases/compiler/narrowedConstInMethod.ts (2 errors) ====
+    
+    function f() {
+        const x: string | null = <any>{};
+        if (x !== null) {
+            return {
+                bar() { return x.length; }  // Error: possibly null x
+                               ~
+!!! error TS2531: Object is possibly 'null'.
+            };
+        }
+    }
+    
+    function f2() {
+        const x: string | null = <any>{};
+        if (x !== null) {
+            return class {
+                bar() { return x.length; }  // Error: possibly null x
+                               ~
+!!! error TS2531: Object is possibly 'null'.
+            };
+        }
+    }

tests/baselines/reference/narrowedConstInMethod.js

@@ -0,0 +1,40 @@
+//// [narrowedConstInMethod.ts]
+
+function f() {
+    const x: string | null = <any>{};
+    if (x !== null) {
+        return {
+            bar() { return x.length; }  // Error: possibly null x
+        };
+    }
+}
+
+function f2() {
+    const x: string | null = <any>{};
+    if (x !== null) {
+        return class {
+            bar() { return x.length; }  // Error: possibly null x
+        };
+    }
+}
+
+//// [narrowedConstInMethod.js]
+function f() {
+    var x = {};
+    if (x !== null) {
+        return {
+            bar: function () { return x.length; } // Error: possibly null x
+        };
+    }
+}
+function f2() {
+    var x = {};
+    if (x !== null) {
+        return (function () {
+            function class_1() {
+            }
+            class_1.prototype.bar = function () { return x.length; }; // Error: possibly null x
+            return class_1;
+        }());
+    }
+}

tests/cases/compiler/narrowedConstInMethod.ts

@@ -0,0 +1,19 @@
+// @strictNullChecks: true
+
+function f() {
+    const x: string | null = <any>{};
+    if (x !== null) {
+        return {
+            bar() { return x.length; }  // Error: possibly null x
+        };
+    }
+}
+
+function f2() {
+    const x: string | null = <any>{};
+    if (x !== null) {
+        return class {
+            bar() { return x.length; }  // Error: possibly null x
+        };
+    }
+}