Revert of Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

src/effects/SkDropShadowImageFilter.cpp

Index: src/effects/SkDropShadowImageFilter.cpp
diff --git a/src/effects/SkDropShadowImageFilter.cpp b/src/effects/SkDropShadowImageFilter.cpp
index 5bbb958e9cc8852e0a6281c255bef986eb95b9b8..0ba8b234b7977f2ed18823c5e6e68b9c43f40fed 100644
--- a/src/effects/SkDropShadowImageFilter.cpp
+++ b/src/effects/SkDropShadowImageFilter.cpp
@@ -28,6 +28,24 @@
     , fShadowMode(shadowMode)
 {
 }
+
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkDropShadowImageFilter::SkDropShadowImageFilter(SkReadBuffer& buffer)
+ : INHERITED(1, buffer) {
+    fDx = buffer.readScalar();
+    fDy = buffer.readScalar();
+    fSigmaX = buffer.readScalar();
+    fSigmaY = buffer.readScalar();
+    fColor = buffer.readColor();
+    fShadowMode = buffer.isVersionLT(SkReadBuffer::kDropShadowMode_Version) ?
+                  kDrawShadowAndForeground_ShadowMode :
+                  static_cast<ShadowMode>(buffer.readInt());
+    buffer.validate(SkScalarIsFinite(fDx) &&
+                    SkScalarIsFinite(fDy) &&
+                    SkScalarIsFinite(fSigmaX) &&
+                    SkScalarIsFinite(fSigmaY));
+}
+#endif
 
 SkFlattenable* SkDropShadowImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);