Revert "share constructors/enum in both variants of SkReadBuffer"

This reverts commit 2ae3337991.

Reason for revert: broke google3

Original change's description:
> share constructors/enum in both variants of SkReadBuffer
> 
> Bug: skia:
> Change-Id: I5a90e1f9a9687df2dd2f69d96ac805bf244cec50
> Reviewed-on: https://skia-review.googlesource.com/c/179844
> Reviewed-by: Mike Reed <reed@google.com>
> Commit-Queue: Mike Reed <reed@google.com>
> Auto-Submit: Mike Reed <reed@google.com>

TBR=reed@google.com

Change-Id: I4735fe2336974240edab0eb7ef23f93d461c0bdf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/179857
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>

src/core/SkReadBuffer.h

@@ -25,6 +25,8 @@
 class SkData;
 class SkImage;
 
+#ifndef SK_DISABLE_READBUFFER
+
 class SkReadBuffer {
 public:
     SkReadBuffer();
@@ -45,8 +47,6 @@ public:
         kSerializeFonts_Version            = 67,
     };
 
-#ifndef SK_DISABLE_READBUFFER
-
     /**
      *  Returns true IFF the version is older than the specified version.
      */
@@ -227,9 +227,30 @@ private:
     }
 
     bool fError = false;
+};
 
 #else // #ifndef SK_DISABLE_READBUFFER
 
+class SkReadBuffer {
+public:
+    SkReadBuffer() {}
+    SkReadBuffer(const void*, size_t) {}
+
+    enum Version {
+        kTileModeInBlurImageFilter_Version = 56,
+        kTileInfoInSweepGradient_Version   = 57,
+        k2PtConicalNoFlip_Version          = 58,
+        kRemovePictureImageFilterLocalSpace = 59,
+        kRemoveHeaderFlags_Version         = 60,
+        kTwoColorDrawShadow_Version        = 61,
+        kDontNegateImageSize_Version       = 62,
+        kStoreImageBounds_Version          = 63,
+        kRemoveOccluderFromBlurMaskFilter  = 64,
+        kFloat4PaintColor_Version          = 65,
+        kSaveBehind_Version                = 66,
+        kSerializeFonts_Version            = 67,
+    };
+
     bool isVersionLT(Version) const { return false; }
     uint32_t getVersion() const { return 0xffffffff; }
     void     setVersion(int) {}
@@ -311,7 +332,8 @@ private:
         static const SkDeserialProcs procs;
         return procs;
     }
-#endif
 };
 
+#endif // #ifndef SK_DISABLE_READBUFFER
+
 #endif // SkReadBuffer_DEFINED