Make storage_read/write return nothing

ethcore/wasm/src/env.rs

@@ -25,12 +25,12 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 	Static(
 		"_storage_read",
 		&[I32; 2],
-		Some(I32),
+		None,
 	),
 	Static(
 		"_storage_write",
 		&[I32; 2],
-		Some(I32),
+		None,
 	),
 	Static(
 		"_balance",

ethcore/wasm/src/runtime.rs

@@ -168,7 +168,7 @@ impl<'a, 'b> Runtime<'a, 'b> {
 
 		self.ext.set_storage(key, val).map_err(|_| UserTrap::StorageUpdateError)?;
 
-		Ok(Some(0i32.into()))
+		Ok(None)
 	}
 
 	/// Read from the storage to wasm memory
@@ -184,7 +184,7 @@ impl<'a, 'b> Runtime<'a, 'b> {
 
 		self.memory.set(val_ptr as u32, &*val)?;
 
-		Ok(Some(0.into()))
+		Ok(None)
 	}
 
 	/// Fetches balance for address