tint/resolver: Reduce small-vector sizes

The vector sizes for expression traversal were excessive.
Reduce.

Change-Id: I3a2b7e7ba4cd82310565b883f85322834275ea8a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/98082
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/src/tint/resolver/resolver.cc b/src/tint/resolver/resolver.cc
index 4295bab..ab25bfb 100644
--- a/src/tint/resolver/resolver.cc
+++ b/src/tint/resolver/resolver.cc
@@ -1276,7 +1276,7 @@
 }
 
 sem::Expression* Resolver::Expression(const ast::Expression* root) {
-    utils::Vector<const ast::Expression*, 128> sorted;
+    utils::Vector<const ast::Expression*, 64> sorted;
     constexpr size_t kMaxExpressionDepth = 512U;
     bool failed = false;
     if (!ast::TraverseExpressions<ast::TraverseOrder::RightToLeft>(