Make ASSERT reference the conditional expression.

This should prevent further unexpected bot breakage due to
unreferenced variables in the ASSERT expression.

Also remove the no longer needed variable referencing macro.

BUG=angleproject:1586

Change-Id: I127695165bdfe39c51fe8d17e00daf6bf2fa8252
Reviewed-on: https://chromium-review.googlesource.com/404948
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/common/debug.cpp b/src/common/debug.cpp
index 746da5e..f64d932 100644
--- a/src/common/debug.cpp
+++ b/src/common/debug.cpp
@@ -171,4 +171,9 @@
     }
 }
 
+std::ostream &DummyStream()
+{
+    return std::cout;
 }
+
+}  // namespace gl