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/SkTwoPointRadialGradient.cpp b/src/effects/gradients/SkTwoPointRadialGradient.cpp
index 3e40044..8ce3f43 100644
--- a/src/effects/gradients/SkTwoPointRadialGradient.cpp
+++ b/src/effects/gradients/SkTwoPointRadialGradient.cpp
@@ -343,17 +343,6 @@
 }
 #endif
 
-#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
-SkTwoPointRadialGradient::SkTwoPointRadialGradient(SkReadBuffer& buffer)
-    : INHERITED(buffer),
-      fCenter1(buffer.readPoint()),
-      fCenter2(buffer.readPoint()),
-      fRadius1(buffer.readScalar()),
-      fRadius2(buffer.readScalar()) {
-    init();
-};
-#endif
-
 SkFlattenable* SkTwoPointRadialGradient::CreateProc(SkReadBuffer& buffer) {
     DescriptorScope desc;
     if (!desc.unflatten(buffer)) {
@@ -686,7 +675,7 @@
                                                    const SkMatrix* localMatrix, GrColor* paintColor,
                                                    GrFragmentProcessor** fp)  const {
     SkASSERT(context);
-    
+
     // invert the localM, translate to center1 (fPtsToUni), rotate so center2 is on x axis.
     SkMatrix matrix;
     if (!this->getLocalMatrix().invert(&matrix)) {
@@ -712,7 +701,7 @@
 
     *paintColor = SkColor2GrColorJustAlpha(paint.getColor());
     *fp = GrRadial2Gradient::Create(context, *this, matrix, fTileMode);
-    
+
     return true;
 }