Remove sem::AccessControl

In preparation for implementing
https://github.com/gpuweb/gpuweb/issues/1604, this change removes the
sem::AccessControl node. Instead, the ast::AccessControl::Access enum is
now on the sem::StorageTexture class, as well as on sem::Variable. For
sem::Variable, the field is set when the variable's type is either a
storage buffer or a storage texture.

Bug: tint:802
Change-Id: Id479af36b401d067b015027923f4e715f5f69f25
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/51020
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
diff --git a/src/sem/variable.h b/src/sem/variable.h
index ba6118f..49f2340 100644
--- a/src/sem/variable.h
+++ b/src/sem/variable.h
@@ -17,6 +17,7 @@
 
 #include <vector>
 
+#include "src/ast/access_control.h"
 #include "src/ast/storage_class.h"
 #include "src/sem/expression.h"
 
@@ -41,9 +42,11 @@
   /// @param declaration the AST declaration node
   /// @param type the variable type
   /// @param storage_class the variable storage class
+  /// @param access_control the variable access control type
   Variable(const ast::Variable* declaration,
            const sem::Type* type,
-           ast::StorageClass storage_class);
+           ast::StorageClass storage_class,
+           ast::AccessControl::Access access_control);
 
   /// Constructor for overridable pipeline constants
   /// @param declaration the AST declaration node
@@ -65,6 +68,9 @@
   /// @returns the storage class for the variable
   ast::StorageClass StorageClass() const { return storage_class_; }
 
+  /// @returns the access control for the variable
+  ast::AccessControl::Access AccessControl() const { return access_control_; }
+
   /// @returns the expressions that use the variable
   const std::vector<const VariableUser*>& Users() const { return users_; }
 
@@ -81,6 +87,7 @@
   const ast::Variable* const declaration_;
   const sem::Type* const type_;
   ast::StorageClass const storage_class_;
+  ast::AccessControl::Access const access_control_;
   std::vector<const VariableUser*> users_;
   const bool is_pipeline_constant_;
   const uint16_t constant_id_ = 0;