ast: Remove unused Struct::set_decorations()

Bug: tint:390
Change-Id: If0aeb618ef15c64e7379501ec88a448bc4d7e015
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/35013
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/ast/struct.h

@@ -52,11 +52,6 @@ class Struct : public Castable<Struct, Node> {
 
   ~Struct() override;
 
-  /// Sets the struct decoration
-  /// @param decos the list of decorations to set
-  void set_decorations(StructDecorationList decos) {
-    decorations_ = std::move(decos);
-  }
   /// @returns the struct decorations
   const StructDecorationList& decorations() const { return decorations_; }
 

src/ast/struct_member.h

@@ -56,11 +56,7 @@ class StructMember : public Castable<StructMember, Node> {
   const std::string& name() const { return name_; }
   /// @returns the type
   type::Type* type() const { return type_; }
-  /// Sets the decorations
-  /// @param decorations the decorations
-  void set_decorations(StructMemberDecorationList decorations) {
-    decorations_ = std::move(decorations);
-  }
+
   /// @returns the decorations
   const StructMemberDecorationList& decorations() const { return decorations_; }