EGL: Implement EGL Image extensions.

BUG=angleproject:2507

Change-Id: Ica33166e9e23e933977c3ab034d4f5a8cada9fb1
Reviewed-on: https://chromium-review.googlesource.com/1143454
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/common/utilities.cpp b/src/common/utilities.cpp
index 460845c..1981849 100644
--- a/src/common/utilities.cpp
+++ b/src/common/utilities.cpp
@@ -970,6 +970,12 @@
             return EGL_NONE;
     }
 }
+
+EGLClientBuffer GLObjectHandleToEGLClientBuffer(GLuint handle)
+{
+    return reinterpret_cast<EGLClientBuffer>(static_cast<uintptr_t>(handle));
+}
+
 }  // namespace gl_egl
 
 #if !defined(ANGLE_ENABLE_WINDOWS_STORE)