Fix integer overflow in ObjectPainter and divide by zero in Color.

third_party/WebKit/Source/platform/graphics/Color.cpp

Index: third_party/WebKit/Source/platform/graphics/Color.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/Color.cpp b/third_party/WebKit/Source/platform/graphics/Color.cpp
index 14f8de3133716bb6cf00d3d96ed0b6d7105bc270..3ad2e4d84d59cb85ee67ae9928e4615f93b9b2ee 100644
--- a/third_party/WebKit/Source/platform/graphics/Color.cpp
+++ b/third_party/WebKit/Source/platform/graphics/Color.cpp
@@ -310,7 +310,7 @@ Color Color::dark() const {
   getRGBA(r, g, b, a);
 
   float v = std::max(r, std::max(g, b));
-  float multiplier = std::max(0.0f, (v - 0.33f) / v);
+  float multiplier = (v == 0.0f) ? 0.0f : std::max(0.0f, (v - 0.33f) / v);
 
   return Color(static_cast<int>(multiplier * r * scaleFactor),
                static_cast<int>(multiplier * g * scaleFactor),