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/SearchSymbol.cpp b/src/compiler/translator/SearchSymbol.cpp
index fb7a6cd..cccd4d3 100644
--- a/src/compiler/translator/SearchSymbol.cpp
+++ b/src/compiler/translator/SearchSymbol.cpp
@@ -12,7 +12,9 @@
 
 namespace sh
 {
-SearchSymbol::SearchSymbol(const TString &symbol) : mSymbol(symbol)
+SearchSymbol::SearchSymbol(const TString &symbol)
+    : TIntermTraverser(true, false, false),
+      mSymbol(symbol)
 {
     match = false;
 }