Switch AlphaThresholdFilter over to new onFilterImage interface

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 6cbdf625fbd868c14aaae6a7a71c0b9396039237..3470c54b8909a18b20b183529afb12c316186bf4 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -414,7 +414,7 @@ bool SkImageFilter::filterImageGPUDeprecated(Proxy* proxy, const SkBitmap& src,
     GrContext* context = srcTexture->getContext();
 
     GrSurfaceDesc desc;
-    desc.fFlags = kRenderTarget_GrSurfaceFlag,
+    desc.fFlags = kRenderTarget_GrSurfaceFlag;
     desc.fWidth = bounds.width();
     desc.fHeight = bounds.height();
     desc.fConfig = kRGBA_8888_GrPixelConfig;
@@ -530,8 +530,8 @@ sk_sp<SkSpecialImage> SkImageFilter::applyCropRect(const Context& ctx,
                                                    SkSpecialImage* src,
                                                    SkIPoint* srcOffset,
                                                    SkIRect* bounds) const {
-    SkIRect srcBounds;
-    srcBounds = SkIRect::MakeXYWH(srcOffset->fX, srcOffset->fY, src->width(), src->height());
+    const SkIRect srcBounds = SkIRect::MakeXYWH(srcOffset->x(), srcOffset->y(),
+                                                src->width(), src->height());
 
     SkIRect dstBounds = this->onFilterNodeBounds(srcBounds, ctx.ctm(), kForward_MapDirection);
     fCropRect.applyTo(dstBounds, ctx.ctm(), this->affectsTransparentBlack(), bounds);