Remove LocalReferencedBuiltinVariables()

It ignored entry point builtin parameters, meaning it was mostly useless.
Was only used by the FirstIndexOffset, which has been re-written.

Change-Id: I26abd69201576cf33b1a71e8e6a1b914871a2a74
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/47223
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: James Price <jrprice@google.com>
diff --git a/src/semantic/function.h b/src/semantic/function.h
index 6301374..d3ee7cd 100644
--- a/src/semantic/function.h
+++ b/src/semantic/function.h
@@ -136,11 +136,6 @@
   /// @returns the referenced storage textures
   VariableBindings ReferencedDepthTextureVariables() const;
 
-  /// Retrieves any locally referenced builtin variables
-  /// @returns the <variable, decoration> pairs.
-  std::vector<std::pair<const Variable*, ast::BuiltinDecoration*>>
-  LocalReferencedBuiltinVariables() const;
-
   /// Checks if the given entry point is an ancestor
   /// @param sym the entry point symbol
   /// @returns true if `sym` is an ancestor entry point of this function
diff --git a/src/semantic/sem_function.cc b/src/semantic/sem_function.cc
index 97e94af..511f862 100644
--- a/src/semantic/sem_function.cc
+++ b/src/semantic/sem_function.cc
@@ -170,21 +170,6 @@
   return ret;
 }
 
-std::vector<std::pair<const Variable*, ast::BuiltinDecoration*>>
-Function::LocalReferencedBuiltinVariables() const {
-  std::vector<std::pair<const Variable*, ast::BuiltinDecoration*>> ret;
-
-  for (auto* var : LocalReferencedModuleVariables()) {
-    for (auto* deco : var->Declaration()->decorations()) {
-      if (auto* builtin = deco->As<ast::BuiltinDecoration>()) {
-        ret.push_back({var, builtin});
-        break;
-      }
-    }
-  }
-  return ret;
-}
-
 bool Function::HasAncestorEntryPoint(Symbol symbol) const {
   for (const auto& point : ancestor_entry_points_) {
     if (point == symbol) {