message: Add WasmSlice::is_empty
diff: @@ -197,6 +197,12 @@ impl<'a, T: ValueType> WasmSlice<'a, T> {
  self.len
  }
  + /// Return if the slice is empty.
  + #[inline]
  + pub fn is_empty(&self) -> bool {
  + self.len == 0
  + }
  +
  /// Get a `WasmRef` to an element in the slice.
  #[inline]
  pub fn index(self, idx: u64) -> WasmRef<'a, T> {
  