Fixing the drawing of blurred shodows for hairline paths with software rendering

BUG=http://code.google.com/p/chromium/issues/detail?id=121251
REVIEW=http://codereview.appspot.com/5981053/



git-svn-id: http://skia.googlecode.com/svn/trunk@3592 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 9113fba..750a4aa 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -899,7 +899,8 @@
     SkMask  srcM, dstM;
 
     if (!SkDraw::DrawToMask(path, &clip.getBounds(), filter, &matrix, &srcM,
-                            SkMask::kComputeBoundsAndRenderImage_CreateMode)) {
+                            SkMask::kComputeBoundsAndRenderImage_CreateMode,
+                            SkPaint::kFill_Style)) {
         return false;
     }
     SkAutoMaskFreeImage autoSrc(srcM.fImage);