Remove (almost) unused read/writeFunctionPtr API.

src/core/SkReadBuffer.cpp

Index: src/core/SkReadBuffer.cpp
diff --git a/src/core/SkReadBuffer.cpp b/src/core/SkReadBuffer.cpp
index b0a371390bd4aa56eb7d2571c63a51499cc664af..ce87d513661dace26852094b9fb6910e01ced112 100644
--- a/src/core/SkReadBuffer.cpp
+++ b/src/core/SkReadBuffer.cpp
@@ -392,21 +392,3 @@ SkFlattenable* SkReadBuffer::readFlattenable(SkFlattenable::Type ft) {
     }
     return obj.release();
 }
-
-/**
- *  Needs to follow the same pattern as readFlattenable(), but explicitly skip whatever data
- *  has been written.
- */
-void SkReadBuffer::skipFlattenable() {
-    if (fFactoryCount > 0) {
-        if (0 == fReader.readU32()) {
-            return;
-        }
-    } else {
-        if (nullptr == this->readFunctionPtr()) {
-            return;
-        }
-    }
-    uint32_t sizeRecorded = fReader.readU32();
-    fReader.skip(sizeRecorded);
-}