Harden degenerate gradient context handling

src/effects/gradients/SkRadialGradient.cpp

Index: src/effects/gradients/SkRadialGradient.cpp
diff --git a/src/effects/gradients/SkRadialGradient.cpp b/src/effects/gradients/SkRadialGradient.cpp
index b0ef205f44ae28e0d2482aa833f3c9615fa37ccc..18ef3768620f66097f41b681cec68d76916646af 100644
--- a/src/effects/gradients/SkRadialGradient.cpp
+++ b/src/effects/gradients/SkRadialGradient.cpp
@@ -44,7 +44,7 @@ size_t SkRadialGradient::onContextSize(const ContextRec&) const {
 }
 
 SkShader::Context* SkRadialGradient::onCreateContext(const ContextRec& rec, void* storage) const {
-    return new (storage) RadialGradientContext(*this, rec);
+    return CheckedCreateContext<RadialGradientContext>(storage, *this, rec);
 }
 
 SkRadialGradient::RadialGradientContext::RadialGradientContext(