Exclude react-dom when flow checking other builds (#16737)

This is because the HostConfig can't be guaranteed to be consistent with
other code such as code that touches the DOM directly.

Ideally we'd have a more systemic solution to this since it will pop
up for other packages later too.

scripts/flow/config/flowconfig

@@ -13,6 +13,8 @@
 .*/__mocks__/.*
 .*/__tests__/.*
 
+%REACT_RENDERER_FLOW_IGNORES%
+
 [include]
 ../../../node_modules/
 ../../../packages/

scripts/flow/createFlowConfigs.js

@@ -23,16 +23,29 @@ function writeConfig(renderer, isFizzSupported) {
   mkdirp.sync(folder);
 
   const fizzRenderer = isFizzSupported ? renderer : 'custom';
-  const config = configTemplate.replace(
-    '%REACT_RENDERER_FLOW_OPTIONS%',
-    `
+  const config = configTemplate
+    .replace(
+      '%REACT_RENDERER_FLOW_OPTIONS%',
+      `
 module.name_mapper='react-reconciler/inline.${renderer}$$' -> 'react-reconciler/inline-typed'
 module.name_mapper='ReactFiberHostConfig$$' -> 'forks/ReactFiberHostConfig.${renderer}'
 module.name_mapper='react-stream/inline.${renderer}$$' -> 'react-stream/inline-typed'
 module.name_mapper='ReactFizzHostConfig$$' -> 'forks/ReactFizzHostConfig.${fizzRenderer}'
 module.name_mapper='ReactFizzFormatConfig$$' -> 'forks/ReactFizzFormatConfig.${fizzRenderer}'
     `.trim(),
-  );
+    )
+    .replace(
+      '%REACT_RENDERER_FLOW_IGNORES%',
+      renderer === 'dom' || renderer === 'dom-browser'
+        ? ''
+        : // If we're not checking DOM, ignore the DOM package since it
+          // won't be consistent.
+          `
+    .*/packages/react-dom/.*
+    .*/packages/.*/forks/.*.dom.js
+    .*/packages/.*/forks/.*.dom-browser.js
+    `.trim(),
+    );
 
   const disclaimer = `
 # ---------------------------------------------------------------#