Convert vectors to list aliases

This CL converts a few more std::vector<std::unique_ptr<foo>>'s to
FooList aliases.

Change-Id: If0dd672f11beaeabd9e89e82903c2174b11be6e1
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/19103
Reviewed-by: David Neto <dneto@google.com>

src/reader/spirv/function.cc

@@ -92,7 +92,7 @@ bool FunctionEmitter::EmitFunctionDeclaration() {
            << function_.result_id();
   }
 
-  std::vector<std::unique_ptr<ast::Variable>> ast_params;
+  ast::VariableList ast_params;
   function_.ForEachParam(
       [this, &ast_params](const spvtools::opt::Instruction* param) {
         auto* ast_type = parser_impl_.ConvertType(param->type_id());

src/reader/spirv/function.h

@@ -53,9 +53,7 @@ class FunctionEmitter {
   bool failed() const { return !success(); }
 
   /// @returns the body of the function.
-  const std::vector<std::unique_ptr<ast::Statement>>& ast_body() {
-    return ast_body_;
-  }
+  const ast::StatementList& ast_body() { return ast_body_; }
 
   /// Records failure.
   /// @returns a FailStream on which to emit diagnostics.
@@ -91,7 +89,7 @@ class FunctionEmitter {
   FailStream& fail_stream_;
   Namer& namer_;
   const spvtools::opt::Function& function_;
-  std::vector<std::unique_ptr<ast::Statement>> ast_body_;
+  ast::StatementList ast_body_;
 };
 
 }  // namespace spirv

src/reader/spirv/parser_impl_test_helper.h

@@ -66,8 +66,7 @@ class SpvParserTest : public testing::Test {
 /// Returns the string dump of a function body.
 /// @param body the statement in the body
 /// @returnss the string dump of a function body.
-inline std::string ToString(
-    const std::vector<std::unique_ptr<ast::Statement>>& body) {
+inline std::string ToString(const ast::StatementList& body) {
   std::ostringstream outs;
   for (const auto& stmt : body) {
     stmt->to_str(outs, 0);