Harden degenerate gradient context handling

src/effects/gradients/SkTwoPointConicalGradient.cpp

Index: src/effects/gradients/SkTwoPointConicalGradient.cpp
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.cpp b/src/effects/gradients/SkTwoPointConicalGradient.cpp
index fd48a6267938edc726956acb9ab6de93e02b4aa4..599fd4c9fdca91791fbf0d26ca7337f0c4412814 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/effects/gradients/SkTwoPointConicalGradient.cpp
@@ -216,7 +216,7 @@ size_t SkTwoPointConicalGradient::onContextSize(const ContextRec&) const {
 
 SkShader::Context* SkTwoPointConicalGradient::onCreateContext(const ContextRec& rec,
                                                               void* storage) const {
-    return new (storage) TwoPointConicalGradientContext(*this, rec);
+    return CheckedCreateContext<TwoPointConicalGradientContext>(storage, *this, rec);
 }
 
 SkTwoPointConicalGradient::TwoPointConicalGradientContext::TwoPointConicalGradientContext(