chore(spv): remove unused MergeInstruction

naga/src/front/spv/function.rs

@@ -8,12 +8,6 @@ use crate::proc::Emitter;
 
 pub type BlockId = u32;
 
-#[derive(Copy, Clone, Debug)]
-pub struct MergeInstruction {
-    pub merge_block_id: BlockId,
-    pub continue_block_id: Option<BlockId>,
-}
-
 impl<I: Iterator<Item = u32>> super::Frontend<I> {
     // Registers a function call. It will generate a dummy handle to call, which
     // gets resolved after all the functions are processed.