wasm: Add support for passive data and element segments (#1389)

This is part of the bulk memory and reference types proposals.

cranelift/wasm/src/translation_utils.rs

@@ -57,6 +57,16 @@ entity_impl!(MemoryIndex);
 pub struct SignatureIndex(u32);
 entity_impl!(SignatureIndex);
 
+/// Index type of a passive data segment inside the WebAssembly module.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
+pub struct PassiveDataIndex(u32);
+entity_impl!(PassiveDataIndex);
+
+/// Index type of a passive element segment inside the WebAssembly module.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
+pub struct PassiveElemIndex(u32);
+entity_impl!(PassiveElemIndex);
+
 /// WebAssembly global.
 #[derive(Debug, Clone, Copy, Hash)]
 pub struct Global {