DevTools: fix backend activation (facebook#26779)

## Summary
We have a case:
1. Open components tab
2. Close Chrome / Firefox devtools window completely
3. Reopen browser devtools panel
4. Open components tab

Currently, in version 4.27.6, we cannot load the components tree.

This PR contains two changes:
- non-functional refactoring in
`react-devtools-shared/src/devtools/store.js`: removed some redundant
type castings.
- fixed backend manager logic (introduced in
facebook#26615) to activate already
registered backends. Looks like frontend of devtools also depends on
`renderer-attached` event, without it component tree won't load.

## How did you test this change?
This fixes the case mentioned prior. Currently in 4.27.6 version it is
not working, we need to refresh the page to make it work.

I've tested this in several environments: chrome, firefox, standalone
with RN application.

packages/react-devtools-extensions/src/backendManager.js

@@ -61,6 +61,13 @@ function setup(hook: ?DevToolsHook) {
   hook.renderers.forEach(renderer => {
     registerRenderer(renderer);
   });
+
+  // Activate and remove from required all present backends, registered within the hook
+  hook.backends.forEach((_, backendVersion) => {
+    requiredBackends.delete(backendVersion);
+    activateBackend(backendVersion, hook);
+  });
+
   updateRequiredBackends();
 
   // register renderers that inject themselves later.

packages/react-devtools-extensions/src/background.js

@@ -28,9 +28,10 @@ async function dynamicallyInjectContentScripts() {
     // For some reason dynamically injected scripts might be already registered
     // Registering them again will fail, which will result into
     // __REACT_DEVTOOLS_GLOBAL_HOOK__ hook not being injected
-    await chrome.scripting.unregisterContentScripts({
-      ids: contentScriptsToInject.map(s => s.id),
-    });
+
+    // Not specifying ids, because Chrome throws an error
+    // if id of non-injected script is provided
+    await chrome.scripting.unregisterContentScripts();
 
     // equivalent logic for Firefox is in prepareInjection.js
     // Manifest V3 method of injecting content script

packages/react-devtools-shared/src/backend/index.js

@@ -15,7 +15,7 @@ import {hasAssignedBackend} from './utils';
 
 import type {DevToolsHook, ReactRenderer, RendererInterface} from './types';
 
-// this is the backend that is compactible with all older React versions
+// this is the backend that is compatible with all older React versions
 function isMatchingRender(version: string): boolean {
   return !hasAssignedBackend(version);
 }
@@ -31,6 +31,7 @@ export function initBackend(
     // DevTools didn't get injected into this page (maybe b'c of the contentType).
     return () => {};
   }
+
   const subs = [
     hook.sub(
       'renderer-attached',
@@ -64,10 +65,6 @@ export function initBackend(
   ];
 
   const attachRenderer = (id: number, renderer: ReactRenderer) => {
-    // skip if already attached
-    if (renderer.attached) {
-      return;
-    }
     // only attach if the renderer is compatible with the current version of the backend
     if (!isMatchingRender(renderer.reconcilerVersion || renderer.version)) {
       return;
@@ -102,7 +99,6 @@ export function initBackend(
     } else {
       hook.emit('unsupported-renderer-version', id);
     }
-    renderer.attached = true;
   };
 
   // Connect renderers that have already injected themselves.

packages/react-devtools-shared/src/backend/types.js

@@ -171,8 +171,6 @@ export type ReactRenderer = {
   // 18.0+
   injectProfilingHooks?: (profilingHooks: DevToolsProfilingHooks) => void,
   getLaneLabelMap?: () => Map<Lane, string> | null,
-  // set by backend after successful attaching
-  attached?: boolean,
   ...
 };