Change parse() to not reuse static field for parsed result

Fixes bug where parse() will return the same object for every
call if called inside an arrow function passed to
Array.prototype.map()

src/marked.ts

@@ -58,13 +58,14 @@ export class Marked {
    */
   static parse(src: string, options: MarkedOptions = this.options): Parsed {
     try {
+      const result = {content: "", meta: {}};
       const { tokens, links, meta } = this.callBlockLexer(src, options);
-      this.parsed.content = this.callParser(tokens, links, options);
-      this.parsed.meta = meta;
-      return this.parsed;
+      result.content = this.callParser(tokens, links, options);
+      result.meta = meta;
+      return result;
     } catch (e) {
-      this.parsed.content = this.callMe(e);
-      return this.parsed;
+      result.content = this.callMe(e);
+      return result;
     }
   }