Revert[2] SkDraw and all Blitters to use pixmap instead of bitmapi

This reverts commit b3f0ec9f9967da2f80f0d842cb7fd53617b48de3.

BUG=skia:

Review URL: https://codereview.chromium.org/1168303006
diff --git a/src/gpu/GrSWMaskHelper.h b/src/gpu/GrSWMaskHelper.h
index a69e4be..b90205b 100644
--- a/src/gpu/GrSWMaskHelper.h
+++ b/src/gpu/GrSWMaskHelper.h
@@ -69,7 +69,7 @@
     
     // Reset the internal bitmap
     void clear(uint8_t alpha) {
-        fBM.eraseColor(SkColorSetARGB(alpha, alpha, alpha, alpha));
+        fPixels.erase(SkColorSetARGB(alpha, 0xFF, 0xFF, 0xFF));
     }
 
     // Canonical usage utility that draws a single path and uploads it
@@ -105,7 +105,7 @@
 
     GrContext*      fContext;
     SkMatrix        fMatrix;
-    SkBitmap        fBM;
+    SkAutoPixmapStorage fPixels;
     SkDraw          fDraw;
     SkRasterClip    fRasterClip;