Disable JS urls at build level for www (#15230)

This will be on by default in open source for the next major.

Author: sebmarkbage

packages/shared/forks/ReactFeatureFlags.www.js

@@ -16,7 +16,6 @@ export const {
   debugRenderPhaseSideEffectsForStrictMode,
   replayFailedUnitOfWorkWithInvokeGuardedCallback,
   warnAboutDeprecatedLifecycles,
-  disableJavaScriptURLs,
   disableYielding,
   disableInputAttributeSyncing,
   warnAboutShorthandPropertyCollision,
@@ -39,6 +38,8 @@ export const enableStableConcurrentModeAPIs = false;
 
 export const enableSuspenseServerRenderer = true;
 
+export const disableJavaScriptURLs = true;
+
 // I've chosen to make this a static flag instead of a dynamic flag controlled
 // by a GK so that it doesn't increase bundle size. It should still be easy
 // to rollback by reverting the commit that turns this on.