formalize named picture versions

BUG=skia:
R=mtklein@google.com, robertphillips@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/291913004

git-svn-id: http://skia.googlecode.com/svn/trunk@14807 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.cpp b/src/effects/gradients/SkTwoPointConicalGradient.cpp
index f25ad50..e26e36b 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/effects/gradients/SkTwoPointConicalGradient.cpp
@@ -351,9 +351,7 @@
     fCenter2(buffer.readPoint()),
     fRadius1(buffer.readScalar()),
     fRadius2(buffer.readScalar()) {
-    if (buffer.pictureVersion() >= 24 || 0 == buffer.pictureVersion()) {
-        fFlippedGrad = buffer.readBool();
-    } else {
+    if (buffer.isVersionLT(SkReadBuffer::kGradientFlippedFlag_Version)) {
         // V23_COMPATIBILITY_CODE
         // Sort gradient by radius size for old pictures
         if (fRadius2 < fRadius1) {
@@ -364,6 +362,8 @@
         } else {
             fFlippedGrad = false;
         }
+    } else {
+        fFlippedGrad = buffer.readBool();
     }
     this->init();
 };