Revert of Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index b5bcc3c5de9b9dbdba9378ec8b93790f44f7782a..5b0e60addebe25ae2bc7867d20e0976ff17c16b4 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -584,6 +584,16 @@
     dst->set(src.fLeft  - pad, src.fTop    - pad,
              src.fRight + pad, src.fBottom + pad);
 }
+
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkBlurMaskFilterImpl::SkBlurMaskFilterImpl(SkReadBuffer& buffer) : SkMaskFilter(buffer) {
+    fSigma = buffer.readScalar();
+    fBlurStyle = (SkBlurStyle)buffer.readInt();
+    fBlurFlags = buffer.readUInt() & SkBlurMaskFilter::kAll_BlurFlag;
+    SkASSERT(fSigma > 0);
+    SkASSERT((unsigned)fBlurStyle <= kLastEnum_SkBlurStyle);
+}
+#endif
 
 SkFlattenable* SkBlurMaskFilterImpl::CreateProc(SkReadBuffer& buffer) {
     const SkScalar sigma = buffer.readScalar();