⏪ 撤销 addStyleSheet 的特性检测/回退

经讨论后认为现代浏览器（Chrome 73+ / Firefox 101+）都已支持
Constructable Stylesheets，main 分支用户基础已跨过临界点；
保留与原实现一致更利于代码维护。

Author: CodFrm

src/app/service/content/utils.test.ts

@@ -458,7 +458,7 @@ describe("utils", () => {
       expect((sheet as any).cssText).toBe(css);
 
       const adopted = (document as any).adoptedStyleSheets as CSSStyleSheet[];
-      expect(adopted.includes(sheet as CSSStyleSheet)).toBe(true);
+      expect(adopted.includes(sheet)).toBe(true);
     });
 
     it("应该在已有样式表的基础上追加新的样式表", () => {
@@ -487,7 +487,7 @@ describe("utils", () => {
       expect((sheet as any).cssText).toBe("");
 
       const adopted = (document as any).adoptedStyleSheets as CSSStyleSheet[];
-      expect(adopted.includes(sheet as CSSStyleSheet)).toBe(true);
+      expect(adopted.includes(sheet)).toBe(true);
     });
 
     it("应该允许添加多个样式表", () => {

src/app/service/content/utils.ts

@@ -222,26 +222,14 @@ export function addStyle(css: string): HTMLStyleElement {
   return document.documentElement.appendChild(dom);
 }
 
-export function addStyleSheet(css: string): CSSStyleSheet | HTMLStyleElement {
+export function addStyleSheet(css: string): CSSStyleSheet {
   // see https://unarist.hatenablog.com/entry/2020/07/06/012540
-  // 旧浏览器（如 Firefox 100 以下）不支持 Constructable Stylesheets / adoptedStyleSheets，回退到 <style> 注入
-  if (
-    typeof CSSStyleSheet === "function" &&
-    typeof CSSStyleSheet.prototype?.replaceSync === "function" &&
-    Array.isArray(document.adoptedStyleSheets)
-  ) {
-    try {
-      const sheet = new CSSStyleSheet();
-      // it might return as Promise
-      sheet.replaceSync(css);
-      // adoptedStyleSheets is FrozenArray so it has to be re-assigned.
-      document.adoptedStyleSheets = document.adoptedStyleSheets.concat(sheet);
-      return sheet;
-    } catch {
-      // 个别环境下 new CSSStyleSheet() 仍可能抛出，落到 <style> fallback
-    }
-  }
-  return addStyle(css);
+  const sheet = new CSSStyleSheet();
+  // it might return as Promise
+  sheet.replaceSync(css);
+  // adoptedStyleSheets is FrozenArray so it has to be re-assigned.
+  document.adoptedStyleSheets = document.adoptedStyleSheets.concat(sheet);
+  return sheet;
 }
 
 export function metadataBlankOrTrue(metadata: SCMetadata, key: string): boolean {