Refactor read and write buffers.

Eliminates SkFlattenable{Read,Write}Buffer, promoting SkOrdered{Read,Write}Buffer
a step each in the hierarchy.

What used to be this:

SkFlattenableWriteBuffer -> SkOrderedWriteBuffer
SkFlattenableReadBuffer  -> SkOrderedReadBuffer
SkFlattenableReadBuffer  -> SkValidatingReadBuffer

is now

SkWriteBuffer
SkReadBuffer -> SkValidatingReadBuffer

Benefits:
  - code is simpler, names are less wordy
  - the generic SkFlattenableFooBuffer code in SkPaint was incorrect; removed
  - write buffers are completely devirtualized, important for record speed

This refactoring was mostly mechanical.  You aren't going to find anything
interesting in files with less than 10 lines changed.

BUG=skia:
R=reed@google.com, scroggo@google.com, djsollen@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/134163010

git-svn-id: http://skia.googlecode.com/svn/trunk@13245 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/gradients/SkSweepGradient.h b/src/effects/gradients/SkSweepGradient.h
index 8b685bc..18d5ddc 100644
--- a/src/effects/gradients/SkSweepGradient.h
+++ b/src/effects/gradients/SkSweepGradient.h
@@ -29,8 +29,8 @@
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSweepGradient)
 
 protected:
-    SkSweepGradient(SkFlattenableReadBuffer& buffer);
-    virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE;
+    SkSweepGradient(SkReadBuffer& buffer);
+    virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE;
 
 private:
     typedef SkGradientShaderBase INHERITED;