Refactor: use forceReset to remount unknown Hooks

We already have the logic to reset a component, so let's just reuse it instead of that special case.

packages/react-fresh/src/ReactFreshBabelPlugin.js

@@ -250,6 +250,7 @@ export default function(babel) {
   function createArgumentsForSignature(node, signature, scope) {
     const {key, customHooks} = signature;
 
+    let forceReset = hasForceResetComment(scope.path);
     let customHooksInScope = [];
     customHooks.forEach(callee => {
       // Check if a correponding binding exists where we emit the signature.
@@ -268,13 +269,12 @@ export default function(babel) {
         customHooksInScope.push(callee);
       } else {
         // We don't have anything to put in the array because Hook is out of scope.
-        // But we can still mark that it exists. This will cause remount on edits.
-        customHooksInScope.push(null);
+        // Since it could potentially have been edited, remount the component.
+        forceReset = true;
       }
     });
 
     const args = [node, t.stringLiteral(key)];
-    const forceReset = hasForceResetComment(scope.path);
     if (forceReset || customHooksInScope.length > 0) {
       args.push(t.booleanLiteral(forceReset));
     }

packages/react-fresh/src/ReactFreshRuntime.js

@@ -59,12 +59,6 @@ function haveEqualSignatures(prevType, nextType) {
   }
 
   for (let i = 0; i < nextCustomHooks.length; i++) {
-    if (prevCustomHooks[i] === undefined || nextCustomHooks[i] === undefined) {
-      // We used a custom Hook, but it isn't in the scope of the signature.
-      // For example this would happen if you define a Hook inline in the component.
-      // This is an edge case, but we'll treat it as always different signature.
-      return false;
-    }
     if (!haveEqualSignatures(prevCustomHooks[i], nextCustomHooks[i])) {
       return false;
     }

packages/react-fresh/src/__tests__/__snapshots__/ReactFreshBabelPlugin-test.js.snap

@@ -67,7 +67,7 @@ export default function App() {
     return foo;
   }
 
-  __signature__(useFancyState, 'useState{[foo, setFoo]}\\nuseFancyEffect{}', false, () => [,]);
+  __signature__(useFancyState, 'useState{[foo, setFoo]}\\nuseFancyEffect{}', true);
 
   const bar = useFancyState();
   const baz = FancyHook.useThing();
@@ -76,7 +76,7 @@ export default function App() {
   return <h1>{bar}{baz}</h1>;
 }
 
-__signature__(App, 'useFancyState{bar}\\nuseThing{baz}\\nuseState{}\\nuseThePlatform{}', false, () => [, FancyHook.useThing,,]);
+__signature__(App, 'useFancyState{bar}\\nuseThing{baz}\\nuseState{}\\nuseThePlatform{}', true, () => [FancyHook.useThing]);
 
 _c = App;