Packager - Fix symbolicate on windows

Summary:
There was an error with packager symbolization on Windows because it looks like `allowHalfOpen: true` doesn't work properly when using named sockets. This uses a random port on localhost for the connection instead on Windows as a workaround.

**Test plan**
Tested that symbolization works on both mac and windows by triggering a warning in UIExplorer.
Closes https://github.com/facebook/react-native/pull/13828

Differential Revision: D5019537

Pulled By: davidaurelio

fbshipit-source-id: 62c5b5f270e553a7d413bb4d1bab2406380f1d4f

packager/src/Server/symbolicate/symbolicate.js

@@ -30,7 +30,11 @@ const affixes = {prefix: 'metro-bundler-symbolicate', suffix: '.sock'};
 const childPath = require.resolve('./worker');
 
 exports.createWorker = (): Symbolicate => {
-  const socket = xpipe.eq(temp.path(affixes));
+  // There are issues with named sockets on windows that cause the connection to
+  // close too early so run the symbolicate server on a random localhost port.
+  const socket = process.platform === 'win32'
+    ? 34712
+    : xpipe.eq(temp.path(affixes));
   const child = new LockingPromise(new LazyPromise(() => startupChild(socket)));
 
   return (stack, sourceMaps) =>
@@ -53,6 +57,7 @@ function startupChild(socket) {
         child.removeAllListeners();
         resolve(child);
       });
+    // $FlowFixMe ChildProcess.send should accept any type.
     child.send(socket);
   });
 }