Make existing unit tests only run on GL contexts

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1869503002

Review URL: https://codereview.chromium.org/1869503002
diff --git a/tests/RectangleTextureTest.cpp b/tests/RectangleTextureTest.cpp
index a4a1cf7..3c2a50d 100644
--- a/tests/RectangleTextureTest.cpp
+++ b/tests/RectangleTextureTest.cpp
@@ -137,7 +137,7 @@
     }
 }
 
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(RectangleTexture, reporter, ctxInfo) {
+DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(RectangleTexture, reporter, ctxInfo) {
     GrContext* context = ctxInfo.fGrContext;
     sk_gpu_test::GLTestContext* glContext = ctxInfo.fGLContext;
     static const int kWidth = 13;