tint/ast: Remove unnecessary ast:: prefixes

These uses are already in the ast namespace, so do not need the extra qualification.

Change-Id: I5e66048c9485c55b72e61ffa5b85b17ba1c780d0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/120761
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
diff --git a/src/tint/ast/struct_member_align_attribute.h b/src/tint/ast/struct_member_align_attribute.h
index 6da1894..1649ae6 100644
--- a/src/tint/ast/struct_member_align_attribute.h
+++ b/src/tint/ast/struct_member_align_attribute.h
@@ -34,7 +34,7 @@
     StructMemberAlignAttribute(ProgramID pid,
                                NodeID nid,
                                const Source& src,
-                               const ast::Expression* align);
+                               const Expression* align);
     ~StructMemberAlignAttribute() override;
 
     /// @returns the WGSL name for the attribute
@@ -47,7 +47,7 @@
     const StructMemberAlignAttribute* Clone(CloneContext* ctx) const override;
 
     /// The align expression
-    const ast::Expression* const expr;
+    const Expression* const expr;
 };
 
 }  // namespace tint::ast