Merge path.crawl ClassDeclaration and Declaration visitors

Merged to avoid subtle assumption that `Declaration` is called before `ClassDeclaration`

packages/babel-traverse/src/scope/index.js

@@ -72,6 +72,14 @@ const collectorVisitor = {
     const parent =
       path.scope.getFunctionParent() || path.scope.getProgramParent();
     parent.registerDeclaration(path);
+
+    // Register class identifier in class' scope if this is a class declaration.
+    if (path.isClassDeclaration() && path.node.id) {
+      const id = path.node.id;
+      const name = id.name;
+
+      path.scope.bindings[name] = parent.getBinding(name);
+    }
   },
 
   ReferencedIdentifier(path, state) {
@@ -131,14 +139,6 @@ const collectorVisitor = {
     scope.getBlockParent().registerDeclaration(path);
   },
 
-  ClassDeclaration(path) {
-    const id = path.node.id;
-    if (!id) return;
-
-    const name = id.name;
-    path.scope.bindings[name] = path.scope.parent.getBinding(name);
-  },
-
   Block(path) {
     const paths = path.get("body");
     for (const bodyPath of (paths: Array)) {