[asmjs] Validator should reject modules with repeated functions.

test/mjsunit/regress/regress-617525.js

Index: test/mjsunit/regress/regress-617525.js
diff --git a/test/mjsunit/regress/regress-617525.js b/test/mjsunit/regress/regress-617525.js
new file mode 100644
index 0000000000000000000000000000000000000000..bb77e06000d51d05ca9ababd0cdca2f60993b50f
--- /dev/null
+++ b/test/mjsunit/regress/regress-617525.js
@@ -0,0 +1,11 @@
+// Copyright 2016 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.
+
+function __f_14() {
+  "use asm";
+  function __f_15() { return 0; }
+  function __f_15() { return 137; }  // redeclared function
+  return {};
+}
+assertThrows(function() { Wasm.instantiateModuleFromAsm(__f_14.toString()) });