Explicitly use global const ctx in offset

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>

naga/src/front/wgsl/lower/mod.rs

@@ -343,7 +343,6 @@ pub enum ExpressionContextType<'temp, 'out> {
 /// [`naga::Function`]: crate::Function
 /// [`Constant`]: ExpressionContextType::Constant
 /// [`naga::Module`]: crate::Module
-/// [`as_const`]: ExpressionContext::as_const
 /// [`Expression::Constant`]: crate::Expression::Constant
 pub struct ExpressionContext<'source, 'temp, 'out> {
     // WGSL AST values.
@@ -372,18 +371,6 @@ pub struct ExpressionContext<'source, 'temp, 'out> {
 }
 
 impl<'source, 'temp, 'out> ExpressionContext<'source, 'temp, 'out> {
-    fn as_const(&mut self) -> ExpressionContext<'source, '_, '_> {
-        ExpressionContext {
-            globals: self.globals,
-            types: self.types,
-            ast_expressions: self.ast_expressions,
-            const_typifier: self.const_typifier,
-            module: self.module,
-            expr_type: ExpressionContextType::Constant(None),
-            global_expression_kind_tracker: self.global_expression_kind_tracker,
-        }
-    }
-
     fn as_global(&mut self) -> GlobalContext<'source, '_, '_> {
         GlobalContext {
             ast_expressions: self.ast_expressions,
@@ -2903,7 +2890,7 @@ impl<'source, 'temp> Lowerer<'source, 'temp> {
 
         let offset = args
             .next()
-            .map(|arg| self.expression(arg, &mut ctx.as_const()))
+            .map(|arg| self.expression(arg, &mut ctx.as_global().as_const()))
             .ok()
             .transpose()?;