remove SkStippleMaskFilter - no external clients

src/effects/SkStippleMaskFilter.cpp

-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkStippleMaskFilter.h"
-#include "SkString.h"
-
-bool SkStippleMaskFilter::filterMask(SkMask* dst,
-                                     const SkMask& src,
-                                     const SkMatrix& matrix,
-                                     SkIPoint* margin) const {
-
-    if (src.fFormat != SkMask::kA8_Format) {
-        return false;
-    }
-
-    dst->fBounds = src.fBounds;
-    dst->fRowBytes = dst->fBounds.width();
-    dst->fFormat = SkMask::kA8_Format;
-    dst->fImage = NULL;
-
-    if (NULL != src.fImage) {
-        size_t dstSize = dst->computeImageSize();
-        if (0 == dstSize) {
-            return false;   // too big to allocate, abort
-        }
-
-        dst->fImage = SkMask::AllocImage(dstSize);
-
-        uint8_t* srcScanLine = src.fImage;
-        uint8_t* scanline = dst->fImage;
-
-        for (int y = 0; y < src.fBounds.height(); ++y) {
-            for (int x = 0; x < src.fBounds.width(); ++x) {
-                scanline[x] = srcScanLine[x] && ((x+y) & 0x1) ? 0xFF : 0x00;
-            }
-            scanline += dst->fRowBytes;
-            srcScanLine += src.fRowBytes;
-        }
-    }
-
-    return true;
-}
-
-#ifndef SK_IGNORE_TO_STRING
-void SkStippleMaskFilter::toString(SkString* str) const {
-    str->append("SkStippleMaskFilter: ()");
-}
-#endif