Revert of Fix SkTextBlob offset semantics. (patchset #2 id:20001 of https://codereview.chromium.org/605533002/)

Reason for revert:
Breaking the Chrome builds with the error:

[14:54:14.317833] ../../skia/ext/pixel_ref_utils.cc:221:16: error: 'drawPosText' marked 'override' but does not override any member functions
[14:54:14.318022]   virtual void drawPosText(const SkDraw& draw,
[14:54:14.318082]                ^

Original issue's description:
> Fix SkTextBlob offset semantics.
>
> Implement proper x/y drawTextBlob() handling by plumbing a
> drawPosText() offset parameter (to act as an additional glyph pos
> translation) throughout the device layer.
>
> The new offset superceeds the existing constY, with a minor semantic
> tweak: whereas previous implementations were ignoring constY in 2D
> positioning mode (scalarsPerGlyph == 2), now the offset is always
> observed, in all positioning modes. We can do this because existing
> drawPosText() clients always pass constY == 0 for full positioning mode.
>
> R=reed@google.com, jvanverth@google.com, robertphillips@google.com
>
> Committed: https://skia.googlesource.com/skia/+/c13bc571d3e61a43b87eb97f0719abd304cafaf2

R=jvanverth@google.com, reed@google.com, bsalomon@google.com, fmalita@chromium.org
TBR=bsalomon@google.com, fmalita@chromium.org, jvanverth@google.com, reed@google.com
NOTREECHECKS=true
NOTRY=true

Author: robertphillips@google.com

Review URL: https://codereview.chromium.org/609223003
diff --git a/src/gpu/GrBitmapTextContext.h b/src/gpu/GrBitmapTextContext.h
index c136270..80abf68 100644
--- a/src/gpu/GrBitmapTextContext.h
+++ b/src/gpu/GrBitmapTextContext.h
@@ -25,8 +25,8 @@
                           SkScalar x, SkScalar y) SK_OVERRIDE;
     virtual void drawPosText(const GrPaint&, const SkPaint&,
                              const char text[], size_t byteLength,
-                             const SkScalar pos[], int scalarsPerPosition,
-                             const SkPoint& offset) SK_OVERRIDE;
+                             const SkScalar pos[], SkScalar constY,
+                             int scalarsPerPosition) SK_OVERRIDE;
 
     virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;