add fsync to try to get complete skps from webpage picture capture

src/core/SkStream.cpp

Index: src/core/SkStream.cpp
diff --git a/src/core/SkStream.cpp b/src/core/SkStream.cpp
index fff8f3382209b9fd9509d55a916b711022d7721e..ef4c6baae437b7c0dd7d780b09bfc852b43377ec 100644
--- a/src/core/SkStream.cpp
+++ b/src/core/SkStream.cpp
@@ -463,6 +463,14 @@ void SkFILEWStream::flush()
     }
 }
 
+void SkFILEWStream::fsync()
+{
+    flush();
+    if (fFILE) {
+        sk_fsync(fFILE);
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////
 
 SkMemoryWStream::SkMemoryWStream(void* buffer, size_t size)