[DevTools] Add DevTools forked Feature flags (#18994)

Also resolve an uncaught error in extension build (#18843).

Co-authored-by: Brian Vaughn <brian.david.vaughn@gmail.com>
Co-authored-by: Brian Vaughn <bvaughn@fb.com>

scripts/flow/createFlowConfigs.js

@@ -53,6 +53,7 @@ module.name_mapper='ReactServerStreamConfig$$' -> 'forks/ReactServerStreamConfig
 module.name_mapper='ReactServerFormatConfig$$' -> 'forks/ReactServerFormatConfig.${serverRenderer}'
 module.name_mapper='ReactFlightServerConfig$$' -> 'forks/ReactFlightServerConfig.${serverRenderer}'
 module.name_mapper='ReactFlightClientHostConfig$$' -> 'forks/ReactFlightClientHostConfig.${serverRenderer}'
+module.name_mapper='react-devtools-feature-flags' -> 'react-devtools-shared/src/config/DevToolsFeatureFlags.default'
     `.trim(),
     )
     .replace('%REACT_RENDERER_FLOW_IGNORES%', ignoredPaths.join('\n'));

scripts/flow/react-devtools.js

@@ -7,4 +7,5 @@
  * @flow
  */
 
-// No types
+declare var __EXTENSION__: boolean;
+declare var __TEST__: boolean;

scripts/jest/config.build-devtools.js

@@ -26,6 +26,9 @@ const packages = readdirSync(packagesRoot).filter(dir => {
 // Create a module map to point React packages to the build output
 const moduleNameMapper = {};
 
+moduleNameMapper['react-devtools-feature-flags'] =
+  '<rootDir>/packages/react-devtools-shared/src/config/DevToolsFeatureFlags.default';
+
 // Map packages to bundles
 packages.forEach(name => {
   // Root entry point

scripts/jest/setupEnvironment.js

@@ -5,6 +5,8 @@ if (NODE_ENV !== 'development' && NODE_ENV !== 'production') {
   throw new Error('NODE_ENV must either be set to development or production.');
 }
 global.__DEV__ = NODE_ENV === 'development';
+global.__EXTENSION__ = false;
+global.__TEST__ = NODE_ENV === 'test';
 global.__PROFILE__ = NODE_ENV === 'development';
 global.__UMD__ = false;
 

scripts/jest/typescript/jest.d.ts

@@ -1,5 +1,7 @@
 declare var jasmine: any;
 declare var __DEV__: boolean;
+declare var __TEST__: boolean;
+declare var __EXTENSION__: boolean;
 
 declare function afterEach(fn: any): any;
 declare function beforeEach(fn: any): any;