🐛 Share prop type names across multiple versions

Fixes #190

Author: Milly

denops_std/buffer/decoration.ts

@@ -5,7 +5,7 @@ import * as nvimFn from "../function/nvim/mod.ts";
 import * as itertools from "https://deno.land/x/itertools@v1.1.0/mod.ts";
 import { unreachable } from "https://deno.land/x/unreachable@v0.1.0/mod.ts";
 
-const cacheKey = Symbol("denops_std/buffer/decoration/vimDecorate/rs");
+const cacheKey = "denops_std/buffer/decoration/vimDecorate/rs@1";
 
 export interface Decoration {
   // Line number