Make imagealphathreshold GM skip replay modes until it is fixed.

TBR=zork@chromium.org

Review URL: https://codereview.chromium.org/94043005

git-svn-id: http://skia.googlecode.com/svn/trunk@12942 2bbb7eff-a529-9590-31e7-b0007b416f81

gm/imagealphathreshold.cpp

@@ -22,7 +22,11 @@ public:
 
 protected:
     virtual uint32_t onGetFlags() const SK_OVERRIDE {
-        return this->INHERITED::onGetFlags() | GM::kSkipTiled_Flag;
+        return this->INHERITED::onGetFlags() |
+               GM::kSkipTiled_Flag |
+               GM::kSkipPicture_Flag |
+               GM::kSkipPipe_Flag | 
+               GM::kSkipPipeCrossProcess_Flag;
     }
 
     virtual SkString onShortName() SK_OVERRIDE {