Remove unused Resolver::TypeDeclInfo.

The TypeDeclInfo Resolver struct is not used. Removed.

Bug: tint:1313
Change-Id: I45eb432c8e7bc2cf4a98ea83cf36e8e6e374e4cd
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/104461
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/tint/resolver/resolver.h

@@ -113,12 +113,6 @@ class Resolver {
   private:
     Validator::ValidTypeStorageLayouts valid_type_storage_layouts_;
 
-    // Structure holding information for a TypeDecl
-    struct TypeDeclInfo {
-        ast::TypeDecl const* const ast;
-        sem::Type* const sem;
-    };
-
     /// Resolves the program, without creating final the semantic nodes.
     /// @returns true on success, false on error
     bool ResolveInternal();