Go bindings: Change generated enum value constants to be typed as the enum type.

mojo/go/tests/enums_test.go

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package tests
+
+import (
+        "mojo/public/interfaces/bindings/tests/test_enums"
+        "testing"
+)
+
+func TestEnums(t *testing.T) {
+        if test_enums.TestEnum_Foo != IdentityEnum1(test_enums.TestEnum_Foo) {
+                t.Errorf("IdentityEnum1 failure.")
+        }
+
+        if test_enums.TestEnum2_Foo != IdentityEnum2(test_enums.TestEnum2_Foo) {
+                t.Errorf("IdentityEnum1 failure.")
+        }
+}
+
+func IdentityEnum1(x test_enums.TestEnum) test_enums.TestEnum {
+        return x
+}
+
+func IdentityEnum2(x test_enums.TestEnum2) test_enums.TestEnum2 {
+        return x
+}