Revert of Revert of Fix SkTextBlob offset semantics.

src/gpu/GrBitmapTextContext.h

Index: src/gpu/GrBitmapTextContext.h
diff --git a/src/gpu/GrBitmapTextContext.h b/src/gpu/GrBitmapTextContext.h
index 6d4ea6d524e255d57e802bbb5c52502c12642625..91e63948bd9a5587285cded44ec6028cba283aeb 100644
--- a/src/gpu/GrBitmapTextContext.h
+++ b/src/gpu/GrBitmapTextContext.h
@@ -24,8 +24,8 @@
                           SkScalar x, SkScalar y) SK_OVERRIDE;
     virtual void drawPosText(const GrPaint&, const SkPaint&,
                              const char text[], size_t byteLength,
-                             const SkScalar pos[], SkScalar constY,
-                             int scalarsPerPosition) SK_OVERRIDE;
+                             const SkScalar pos[], int scalarsPerPosition,
+                             const SkPoint& offset) SK_OVERRIDE;
 
     virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;