[strong] Strong classes can't extend null

test/mjsunit/strong/class-extend-null.js

Index: test/mjsunit/strong/class-extend-null.js
diff --git a/test/mjsunit/strong/class-extend-null.js b/test/mjsunit/strong/class-extend-null.js
new file mode 100644
index 0000000000000000000000000000000000000000..3ed7b36dbb4912765e97b74a615edbdf13efb599
--- /dev/null
+++ b/test/mjsunit/strong/class-extend-null.js
@@ -0,0 +1,97 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --strong-mode --allow-natives-syntax
+
+(function() {
+"use strict";
+
+let foo = null;
+
+function nullLiteral() {
+  class Class1 extends null {
+    constructor() {
+      super();
+    }
+  }
+}
+
+function nullVariable() {
+  class Class2 extends foo {
+    constructor() {
+      super();
+    }
+  }
+}
+
+function nullLiteralClassExpr() {
+  (class extends null {});
+}
+
+function nullVariableClassExpr() {
+  (class extends foo {});
+}
+
+assertDoesNotThrow(nullLiteral);
+%OptimizeFunctionOnNextCall(nullLiteral);
+assertDoesNotThrow(nullLiteral);
+
+assertDoesNotThrow(nullVariable);
+%OptimizeFunctionOnNextCall(nullVariable);
+assertDoesNotThrow(nullVariable);
+
+assertDoesNotThrow(nullLiteralClassExpr);
+%OptimizeFunctionOnNextCall(nullLiteralClassExpr);
+assertDoesNotThrow(nullLiteralClassExpr);
+
+assertDoesNotThrow(nullVariableClassExpr);
+%OptimizeFunctionOnNextCall(nullVariableClassExpr);
+assertDoesNotThrow(nullVariableClassExpr);
+})();
+
+(function() {
+"use strong";
+
+let foo = null;
+
+function nullLiteral() {
+  class Class1 extends null {
+    constructor() {
+      super();
+    }
+  }
+}
+
+function nullVariable() {
+  class Class2 extends foo {
+    constructor() {
+      super();
+    }
+  }
+}
+
+function nullLiteralClassExpr() {
+  (class extends null {});
+}
+
+function nullVariableClassExpr() {
+  (class extends foo {});
+}
+
+assertThrows(nullLiteral, TypeError);
+%OptimizeFunctionOnNextCall(nullLiteral);
+assertThrows(nullLiteral, TypeError);
+
+assertThrows(nullVariable, TypeError);
+%OptimizeFunctionOnNextCall(nullVariable);
+assertThrows(nullVariable, TypeError);
+
+assertThrows(nullLiteralClassExpr, TypeError);
+%OptimizeFunctionOnNextCall(nullLiteralClassExpr);
+assertThrows(nullLiteralClassExpr, TypeError);
+
+assertThrows(nullVariableClassExpr, TypeError);
+%OptimizeFunctionOnNextCall(nullVariableClassExpr);
+assertThrows(nullVariableClassExpr, TypeError);
+})();