One more ASAN fix.

Don't fail the GL validation check if the GL context fails to create.

TBR=robertphillips@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/1096113003

tests/GLInterfaceValidationTest.cpp

@@ -28,7 +28,6 @@ DEF_GPUTEST(GLInterfaceValidation, reporter, factory) {
             continue;
         }
 
-        REPORTER_ASSERT(reporter, glCtx);
         if (glCtx) {
             const GrGLInterface* interface = glCtx->gl();
             REPORTER_ASSERT(reporter, interface->validate());