Move ANGLETest back in test_utils, leaving a proxy header for Chromium

BUG=angleproject:892

Change-Id: Ibd494813be87e996096077d6e208cc92461b8f49
Reviewed-on: https://chromium-review.googlesource.com/271154
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/tests/gl_tests/PbufferTest.cpp b/src/tests/gl_tests/PbufferTest.cpp
index 49045d5..5a085f1 100644
--- a/src/tests/gl_tests/PbufferTest.cpp
+++ b/src/tests/gl_tests/PbufferTest.cpp
@@ -4,7 +4,7 @@
 // found in the LICENSE file.
 //
 
-#include "end2end_tests/ANGLETest.h"
+#include "test_utils/ANGLETest.h"
 
 using namespace angle;