Allow JS constructor function to return non-void

tests/cases/compiler/jsConstructorFunction.ts

@@ -0,0 +1,22 @@
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// @filename: index.js
+// @lib: es5, dom
+var Person = function (firstNameOrPojo, lastName) {
+
+    if (typeof firstNameOrPojo === "string") {
+        this.firstName = firstNameOrPojo;
+        this.lastName = lastName;
+    } else {
+        return new Person(firstNameOrPojo.firstName, firstNameOrPojo.lastName);
+    }
+};
+
+Person.prototype.greet = function greet() {
+    return `Hello, I am ${this.firstName} ${this.lastName}.`;
+};
+
+var fred = new Person({ firstName: "Fred", lastName: "Flintstone" });
+
+console.log(fred.greet());