Remove (almost) unused read/writeFunctionPtr API.

src/core/SkValidatingReadBuffer.cpp

Index: src/core/SkValidatingReadBuffer.cpp
diff --git a/src/core/SkValidatingReadBuffer.cpp b/src/core/SkValidatingReadBuffer.cpp
index a27d42d82dfd26f2600d7a60177c5604f0fd11c6..277951688945d1a83969b168d1d50c8ba2ead766 100644
--- a/src/core/SkValidatingReadBuffer.cpp
+++ b/src/core/SkValidatingReadBuffer.cpp
@@ -281,13 +281,3 @@ SkFlattenable* SkValidatingReadBuffer::readFlattenable(SkFlattenable::Type type)
     }
     return obj.release();
 }
-
-void SkValidatingReadBuffer::skipFlattenable() {
-    SkString name;
-    this->readString(&name);
-    if (fError) {
-        return;
-    }
-    uint32_t sizeRecorded = this->readUInt();
-    this->skip(sizeRecorded);
-}