Clean up TIntermTraverser usage

Remove default parameters from TIntermTraverser.

Also clean up a few dead function declarations in traversers.

TEST=angle_unittests, angle_end2end_tests
BUG=angleproject:1037

Change-Id: I8d126c6c2d5b53e8b14e23e3d102f204a59323b3
Reviewed-on: https://chromium-review.googlesource.com/275184
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/ValidateOutputs.cpp b/src/compiler/translator/ValidateOutputs.cpp
index ac1c10d..614d790 100644
--- a/src/compiler/translator/ValidateOutputs.cpp
+++ b/src/compiler/translator/ValidateOutputs.cpp
@@ -10,7 +10,8 @@
 #include "compiler/translator/ParseContext.h"
 
 ValidateOutputs::ValidateOutputs(TInfoSinkBase& sink, int maxDrawBuffers)
-    : mSink(sink),
+    : TIntermTraverser(true, false, false),
+      mSink(sink),
       mMaxDrawBuffers(maxDrawBuffers),
       mNumErrors(0),
       mHasUnspecifiedOutputLocation(false)