Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

This was needed for pictures before v33, and we're now requiring v35+.

Will follow up with the same for skia/ext/pixel_ref_utils_unittest.cc

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/52c293547b973f7fb5de3c83f5062b07d759ab88

Review URL: https://codereview.chromium.org/769953002
diff --git a/src/effects/gradients/SkRadialGradient.cpp b/src/effects/gradients/SkRadialGradient.cpp
index 99531d9..7c0e8f6 100644
--- a/src/effects/gradients/SkRadialGradient.cpp
+++ b/src/effects/gradients/SkRadialGradient.cpp
@@ -252,14 +252,6 @@
     return kRadial_GradientType;
 }
 
-#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
-SkRadialGradient::SkRadialGradient(SkReadBuffer& buffer)
-    : INHERITED(buffer),
-      fCenter(buffer.readPoint()),
-      fRadius(buffer.readScalar()) {
-}
-#endif
-
 SkFlattenable* SkRadialGradient::CreateProc(SkReadBuffer& buffer) {
     DescriptorScope desc;
     if (!desc.unflatten(buffer)) {
@@ -578,7 +570,7 @@
                                            const SkMatrix* localMatrix, GrColor* paintColor,
                                            GrFragmentProcessor** fp) const {
     SkASSERT(context);
-    
+
     SkMatrix matrix;
     if (!this->getLocalMatrix().invert(&matrix)) {
         return false;
@@ -591,10 +583,10 @@
         matrix.postConcat(inv);
     }
     matrix.postConcat(fPtsToUnit);
-    
+
     *paintColor = SkColor2GrColorJustAlpha(paint.getColor());
     *fp = GrRadialGradient::Create(context, *this, matrix, fTileMode);
-    
+
     return true;
 }