Revert of Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

src/core/SkFilterShader.cpp

Index: src/core/SkFilterShader.cpp
diff --git a/src/core/SkFilterShader.cpp b/src/core/SkFilterShader.cpp
index 48c4b8b477314ba2fbf9a6e64a5859754c7023d7..cb042e604cd71836f999f881dc8632dfa262fbd1 100644
--- a/src/core/SkFilterShader.cpp
+++ b/src/core/SkFilterShader.cpp
@@ -20,6 +20,13 @@
     fFilter = filter;
     filter->ref();
 }
+
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkFilterShader::SkFilterShader(SkReadBuffer& buffer) : INHERITED(buffer) {
+    fShader = buffer.readShader();
+    fFilter = buffer.readColorFilter();
+}
+#endif
 
 SkFilterShader::~SkFilterShader() {
     fFilter->unref();