Fix alpha textures in NV ES3 contexts on Windows.

Make unit tests iterate over all the rendering GL context types rather than using kNative.

Fix the extension printing when gStartupSpew is set.

R=jvanverth@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/398183002
diff --git a/tests/GrContextFactoryTest.cpp b/tests/GrContextFactoryTest.cpp
index 0191f1a..1d884ac 100644
--- a/tests/GrContextFactoryTest.cpp
+++ b/tests/GrContextFactoryTest.cpp
@@ -16,17 +16,17 @@
 
     // Before we ask for a context, we expect the GL context to not be there.
     REPORTER_ASSERT(reporter,
-                    NULL == factory->getGLContext(GrContextFactory::kNative_GLContextType));
+                    NULL == factory->getGLContext(GrContextFactory::kNull_GLContextType));
 
     // After we ask for a context, we expect that the GL context to be there.
-    factory->get(GrContextFactory::kNative_GLContextType);
+    factory->get(GrContextFactory::kNull_GLContextType);
     REPORTER_ASSERT(reporter,
-                    factory->getGLContext(GrContextFactory::kNative_GLContextType) != NULL);
+                    factory->getGLContext(GrContextFactory::kNull_GLContextType) != NULL);
 
     // If we did not ask for a context with the particular GL context, we would
     // expect the particular GL context to not be there.
     REPORTER_ASSERT(reporter,
-                    NULL == factory->getGLContext(GrContextFactory::kNull_GLContextType));
+                    NULL == factory->getGLContext(GrContextFactory::kDebug_GLContextType));
 }
 
 #endif