Remove Blocks (#20138)

* Remove Blocks

* Remove Flight Server Runtime

There's no need for this now that the JSResource is part of the bundler
protocol. Might need something for Webpack plugin specifically later.

* Devtools

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

@@ -17,8 +17,6 @@ import type {LazyComponent} from 'react/src/ReactLazy';
 import type {CurrentDispatcherRef} from './types';
 
 import {
-  BLOCK_NUMBER,
-  BLOCK_SYMBOL_STRING,
   FORWARD_REF_NUMBER,
   FORWARD_REF_SYMBOL_STRING,
   LAZY_NUMBER,
@@ -276,14 +274,6 @@ export function describeUnknownElementTypeFrameInDEV(
           ownerFn,
           currentDispatcherRef,
         );
-      case BLOCK_NUMBER:
-      case BLOCK_SYMBOL_STRING:
-        return describeFunctionComponentFrame(
-          type._render,
-          source,
-          ownerFn,
-          currentDispatcherRef,
-        );
       case LAZY_NUMBER:
       case LAZY_SYMBOL_STRING: {
         const lazyComponent: LazyComponent<any, any> = (type: any);