Fix SkFILEStream.

Change-Id: I8c66e4e3e857227aed3d0bc497982f4c0d96d917
Reviewed-on: https://skia-review.googlesource.com/9498
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 0cb5853..f4c8e8b 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -2111,6 +2111,7 @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#include "SkString.h"
 #include "SkStringUtils.h"
 #include "SkStream.h"