diff --git a/tests/baselines/reference/reactNamespaceJSXEmit.js b/tests/baselines/reference/reactNamespaceJSXEmit.js
index 8282cd628ee..ced18ebc031 100644
--- a/tests/baselines/reference/reactNamespaceJSXEmit.js
+++ b/tests/baselines/reference/reactNamespaceJSXEmit.js
@@ -14,9 +14,10 @@ declare var x: any;
 
 //// [reactNamespaceJSXEmit.js]
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };
diff --git a/tests/baselines/reference/tsxExternalModuleEmit2.js b/tests/baselines/reference/tsxExternalModuleEmit2.js
index cce67693817..25e186e140f 100644
--- a/tests/baselines/reference/tsxExternalModuleEmit2.js
+++ b/tests/baselines/reference/tsxExternalModuleEmit2.js
@@ -20,9 +20,10 @@ declare var Foo, React;
 //// [app.js]
 "use strict";
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };
diff --git a/tests/baselines/reference/tsxReactEmit2.js b/tests/baselines/reference/tsxReactEmit2.js
index e73d8b4b6c8..051c7380171 100644
--- a/tests/baselines/reference/tsxReactEmit2.js
+++ b/tests/baselines/reference/tsxReactEmit2.js
@@ -17,9 +17,10 @@ var spreads5 = <div x={p2} {...p1} y={p3}>{p2}</div>;
 
 //// [file.js]
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };
diff --git a/tests/baselines/reference/tsxReactEmit4.js b/tests/baselines/reference/tsxReactEmit4.js
index e1e7384a463..3b554f17cb7 100644
--- a/tests/baselines/reference/tsxReactEmit4.js
+++ b/tests/baselines/reference/tsxReactEmit4.js
@@ -19,9 +19,10 @@ var spread1 = <div {...p} x={0} />;
 
 //// [file.js]
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };
diff --git a/tests/baselines/reference/tsxReactEmit5.js b/tests/baselines/reference/tsxReactEmit5.js
index e969b587c79..a6dde25edc3 100644
--- a/tests/baselines/reference/tsxReactEmit5.js
+++ b/tests/baselines/reference/tsxReactEmit5.js
@@ -24,9 +24,10 @@ var spread1 = <div x='' {...foo} y='' />;
 //// [react-consumer.js]
 "use strict";
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };
diff --git a/tests/baselines/reference/tsxReactEmit6.js b/tests/baselines/reference/tsxReactEmit6.js
index 95461e0149f..cb41bf4d1eb 100644
--- a/tests/baselines/reference/tsxReactEmit6.js
+++ b/tests/baselines/reference/tsxReactEmit6.js
@@ -29,9 +29,10 @@ namespace M {
 //// [file.js]
 //// [react-consumer.js]
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1; i < arguments.length; i++) {
-        var s = arguments[i];
-        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
     }
     return t;
 };