more versatile scope pushing

src/babel/transformation/transformers/es6/destructuring.js

@@ -135,10 +135,7 @@ export function AssignmentExpression(node, parent, scope, file) {
   if (!t.isPattern(node.left)) return;
 
   var ref = scope.generateUidIdentifier("temp");
-  scope.push({
-    key: ref.name,
-    id: ref
-  });
+  scope.push({ id: ref });
 
   var nodes = [];
   nodes.push(t.assignmentExpression("=", ref, node.right));

src/babel/transformation/transformers/es6/object-super.js

@@ -40,10 +40,7 @@ export function ObjectExpression(node, parent, scope, file) {
   }
 
   if (objectRef) {
-    scope.push({
-      id: objectRef
-    });
-
+    scope.push({ id: objectRef });
     return t.assignmentExpression("=", objectRef, node);
   }
 }

src/babel/traversal/scope.js

@@ -581,16 +581,16 @@ export default class Scope {
       block = block.body;
     }
 
-    if (t.isBlockStatement(block) || t.isProgram(block)) {
-      block._declarations ||= {};
-      block._declarations[opts.key || opts.id.name] = {
-        kind: opts.kind || "var",
-        id: opts.id,
-        init: opts.init
-      };
-    } else {
-      throw new TypeError(`cannot add a declaration here in node type ${block.type}`);
+    if (!t.isBlockStatement(block) && !t.isProgram(block)) {
+      block = this.getBlockParent().block;
     }
+
+    block._declarations ||= {};
+    block._declarations[opts.key || opts.id.name] = {
+      kind: opts.kind || "var",
+      id: opts.id,
+      init: opts.init
+    };
   }
 
   /**

src/babel/types/index.js

@@ -154,7 +154,6 @@ t.toSequenceExpression = function (nodes: Array<Object>, scope: Scope): Object {
       each(node.declarations, function (declar) {
         scope.push({
           kind: node.kind,
-          key: declar.id.name,
           id: declar.id
         });
         exprs.push(t.assignmentExpression("=", declar.id, declar.init));