Fix lots of variable shadowing in ANGLE

BUG=angle:877

Change-Id: I15168ae32605b26aee08274464ffe68adb5a7e87
Reviewed-on: https://chromium-review.googlesource.com/242351
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Austin Kinross <aukinros@microsoft.com>
diff --git a/src/compiler/translator/QualifierAlive.cpp b/src/compiler/translator/QualifierAlive.cpp
index 1f6fb75..3d950aa 100644
--- a/src/compiler/translator/QualifierAlive.cpp
+++ b/src/compiler/translator/QualifierAlive.cpp
@@ -49,7 +49,7 @@
         found = true;
 }
 
-bool TAliveTraverser::visitSelection(Visit preVisit, TIntermSelection* node)
+bool TAliveTraverser::visitSelection(Visit, TIntermSelection*)
 {
     if (wasFound())
         return false;