Bug 1095510 - See if ClearRect has weird data. r=jmuizelaar

--HG--
extra : rebase_source : bc587fc96d30cac3ef829f8ceabc72aae6831a98

gfx/2d/DrawTargetCairo.cpp

@@ -1046,6 +1046,12 @@ DrawTargetCairo::ClearRect(const Rect& aRect)
 {
   AutoPrepareForDrawing prep(this, mContext);
 
+  if (!mContext || aRect.Width() <= 0 || aRect.Height() <= 0 ||
+      !IsFinite(aRect.X()) || !IsFinite(aRect.Width()) ||
+      !IsFinite(aRect.Y()) || !IsFinite(aRect.Height())) {
+    gfxCriticalError() << "ClearRect with invalid argument " << gfx::hexa(mContext) << " with " << aRect.Width() << "x" << aRect.Height() << " [" << aRect.X() << ", " << aRect.Y() << "]";
+  }
+
   cairo_set_antialias(mContext, CAIRO_ANTIALIAS_NONE);
   cairo_new_path(mContext);
   cairo_set_operator(mContext, CAIRO_OPERATOR_CLEAR);