Fix Dash Effect readback calc for fPhase from old skps

src/effects/SkDashPathEffect.cpp

Index: src/effects/SkDashPathEffect.cpp
diff --git a/src/effects/SkDashPathEffect.cpp b/src/effects/SkDashPathEffect.cpp
index 6f132e0be573a568dcda60a45ee11f31d8daecb4..24361bd3697bbbc686f4267c149202507e9d4191 100644
--- a/src/effects/SkDashPathEffect.cpp
+++ b/src/effects/SkDashPathEffect.cpp
@@ -568,7 +568,7 @@ SkDashPathEffect::SkDashPathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {
         for (int i = 0; i < fInitialDashIndex; ++i) {
             fPhase += fIntervals[i];
         }
-        fPhase += fInitialDashLength;
+        fPhase += fIntervals[fInitialDashIndex] - fInitialDashLength;
     } else {
         this->setInternalMembers(fPhase);
     }