remove cruft from SkTypes.h, including SkBool

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1548223002

TBR=

Review URL: https://codereview.chromium.org/1548223002
diff --git a/src/animator/SkScript2.h b/src/animator/SkScript2.h
index d182e8c..f257adb 100644
--- a/src/animator/SkScript2.h
+++ b/src/animator/SkScript2.h
@@ -1,13 +1,14 @@
-
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+
 #ifndef SkScript2_DEFINED
 #define SkScript2_DEFINED
 
+#include "SkDisplayType.h"
 #include "SkOperand2.h"
 #include "SkStream.h"
 #include "SkTDArray.h"