Adding more validation

src/effects/SkMergeImageFilter.cpp

Index: src/effects/SkMergeImageFilter.cpp
diff --git a/src/effects/SkMergeImageFilter.cpp b/src/effects/SkMergeImageFilter.cpp
index 93e23356101c71430716d530113f224b2abf9d0a..9fcc5ff0c59ba9c8e9fbb323822629beaf064b99 100755
--- a/src/effects/SkMergeImageFilter.cpp
+++ b/src/effects/SkMergeImageFilter.cpp
@@ -53,6 +53,7 @@ SkMergeImageFilter::SkMergeImageFilter(SkImageFilter* first, SkImageFilter* seco
 SkMergeImageFilter::SkMergeImageFilter(SkImageFilter* filters[], int count,
                                        const SkXfermode::Mode modes[],
                                        const CropRect* cropRect) : INHERITED(count, filters, cropRect) {
+    SkASSERT(count <= SkImageFilter::kManyInputs);
     this->initModes(modes);
 }
 
@@ -156,7 +157,8 @@ void SkMergeImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
     }
 }
 
-SkMergeImageFilter::SkMergeImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
+SkMergeImageFilter::SkMergeImageFilter(SkFlattenableReadBuffer& buffer)
+  : INHERITED(buffer, SkImageFilter::kManyInputs) {
     bool hasModes = buffer.readBool();
     if (hasModes) {
         this->initAllocModes();