Return Error from onMakeCurrent

- Preliminary change for gl_PointCoords fix for Vulkan.

Bug: angleproject:2673
Change-Id: Ie43e8aeccf75a8daa4a137b98292d848522ea2f0
Reviewed-on: https://chromium-review.googlesource.com/1134877
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Luc Ferron <lucferron@chromium.org>
diff --git a/src/libANGLE/Context.cpp b/src/libANGLE/Context.cpp
index 976fed2..a263510 100644
--- a/src/libANGLE/Context.cpp
+++ b/src/libANGLE/Context.cpp
@@ -632,7 +632,7 @@
     }
 
     // Notify the renderer of a context switch
-    mImplementation->onMakeCurrent(this);
+    ANGLE_TRY(mImplementation->onMakeCurrent(this));
     return egl::NoError();
 }