Fix GLInterfaceValidation test after "Remove GrContextFactory::getGLContext"

tests/GLInterfaceValidationTest.cpp

Index: tests/GLInterfaceValidationTest.cpp
diff --git a/tests/GLInterfaceValidationTest.cpp b/tests/GLInterfaceValidationTest.cpp
index 3632c255a62a8e25be4a92643010cc5b45fd4481..5736e2d2d6724519bd416badb65bdfe20bcabec6 100755
--- a/tests/GLInterfaceValidationTest.cpp
+++ b/tests/GLInterfaceValidationTest.cpp
@@ -17,7 +17,7 @@ DEF_GPUTEST(GLInterfaceValidation, reporter, factory) {
         GrContextFactory::GLContextType glCtxType = (GrContextFactory::GLContextType)i;
         // this forces the factory to make the context if it hasn't yet
         GrContextFactory::ContextInfo* contextInfo = factory->getContextInfo(glCtxType);
-        SkGLContext* glCtx = contextInfo->fGLContext;
+        SkGLContext* glCtx = contextInfo ? contextInfo->fGLContext : nullptr;
 
         // We're supposed to fail the NVPR context type when we the native context that does not
         // support the NVPR extension.