Implement canvas's globalCompositeOperation lighter properly....

skia/sgl/SkDraw.cpp

Index: skia/sgl/SkDraw.cpp
===================================================================
--- skia/sgl/SkDraw.cpp	(revision 14480)
+++ skia/sgl/SkDraw.cpp	(working copy)
@@ -911,11 +911,16 @@
                 return;
             }
         }
+
         mask.fFormat = SkMask::kA8_Format;
         mask.fRowBytes = SkAlign4(mask.fBounds.width());
+        size_t size = mask.computeImageSize();
+        if (0 == size) {
+            // the mask is too big to allocated, draw nothing
+            return;
+        }
 
         // allocate (and clear) our temp buffer to hold the transformed bitmap
-        size_t size = mask.computeImageSize();
         SkAutoMalloc    storage(size);
         mask.fImage = (uint8_t*)storage.get();
         memset(mask.fImage, 0, size);
@@ -2336,7 +2341,12 @@
     if (SkMask::kComputeBoundsAndRenderImage_CreateMode == mode) {
         mask->fFormat = SkMask::kA8_Format;
         mask->fRowBytes = mask->fBounds.width();
-        mask->fImage = SkMask::AllocImage(mask->computeImageSize());
+        size_t size = mask->computeImageSize();
+        if (0 == size) {
+            // we're too big to allocate the mask, abort
+            return false;
+        }
+        mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }