Accepted baselines.

tests/baselines/reference/underscoreThisInDerivedClass01.js

@@ -0,0 +1,56 @@
+//// [underscoreThisInDerivedClass01.ts]
+// @target es5
+
+// Original test intent:
+// When arrow functions capture 'this', the lexical 'this' owner
+// currently captures 'this' using a variable named '_this'.
+// That means that '_this' becomes a reserved identifier in certain places.
+//
+// Constructors have adopted the same identifier name ('_this')
+// for capturing any potential return values from super calls,
+// so we expect the same behavior.
+
+class C {
+    constructor() {
+        return {};
+    }
+}
+
+class D extends C {
+    constructor() {
+        var _this = "uh-oh?";
+        super();
+    }
+}
+
+//// [underscoreThisInDerivedClass01.js]
+// @target es5
+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 __());
+};
+// Original test intent:
+// When arrow functions capture 'this', the lexical 'this' owner
+// currently captures 'this' using a variable named '_this'.
+// That means that '_this' becomes a reserved identifier in certain places.
+//
+// Constructors have adopted the same identifier name ('_this')
+// for capturing any potential return values from super calls,
+// so we expect the same behavior.
+var C = (function () {
+    function C() {
+        return {};
+    }
+    return C;
+}());
+var D = (function (_super) {
+    __extends(D, _super);
+    function D() {
+        var _this;
+        var _this = "uh-oh?";
+        _this = _super.call(this) || this;
+        return _this;
+    }
+    return D;
+}(C));

tests/baselines/reference/underscoreThisInDerivedClass01.symbols

@@ -0,0 +1,32 @@
+=== tests/cases/compiler/underscoreThisInDerivedClass01.ts ===
+// @target es5
+
+// Original test intent:
+// When arrow functions capture 'this', the lexical 'this' owner
+// currently captures 'this' using a variable named '_this'.
+// That means that '_this' becomes a reserved identifier in certain places.
+//
+// Constructors have adopted the same identifier name ('_this')
+// for capturing any potential return values from super calls,
+// so we expect the same behavior.
+
+class C {
+>C : Symbol(C, Decl(underscoreThisInDerivedClass01.ts, 0, 0))
+
+    constructor() {
+        return {};
+    }
+}
+
+class D extends C {
+>D : Symbol(D, Decl(underscoreThisInDerivedClass01.ts, 15, 1))
+>C : Symbol(C, Decl(underscoreThisInDerivedClass01.ts, 0, 0))
+
+    constructor() {
+        var _this = "uh-oh?";
+>_this : Symbol(_this, Decl(underscoreThisInDerivedClass01.ts, 19, 11))
+
+        super();
+>super : Symbol(C, Decl(underscoreThisInDerivedClass01.ts, 0, 0))
+    }
+}

tests/baselines/reference/underscoreThisInDerivedClass01.types

@@ -0,0 +1,35 @@
+=== tests/cases/compiler/underscoreThisInDerivedClass01.ts ===
+// @target es5
+
+// Original test intent:
+// When arrow functions capture 'this', the lexical 'this' owner
+// currently captures 'this' using a variable named '_this'.
+// That means that '_this' becomes a reserved identifier in certain places.
+//
+// Constructors have adopted the same identifier name ('_this')
+// for capturing any potential return values from super calls,
+// so we expect the same behavior.
+
+class C {
+>C : C
+
+    constructor() {
+        return {};
+>{} : {}
+    }
+}
+
+class D extends C {
+>D : D
+>C : C
+
+    constructor() {
+        var _this = "uh-oh?";
+>_this : string
+>"uh-oh?" : string
+
+        super();
+>super() : void
+>super : typeof C
+    }
+}