improve performance (#3020)

- replace `find_if()` with `all()` wherever possible
- move ESTree-specific logic out of `figure_out_scope()`

lib/mozilla-ast.js

@@ -564,6 +564,21 @@
         FROM_MOZ_STACK = [];
         var ast = from_moz(node);
         FROM_MOZ_STACK = save_stack;
+        ast.walk(new TreeWalker(function(node) {
+            if (node instanceof AST_LabelRef) {
+                for (var level = 0, parent; parent = this.parent(level); level++) {
+                    if (parent instanceof AST_Scope) break;
+                    if (parent instanceof AST_LabeledStatement && parent.label.name == node.name) {
+                        node.thedef = parent.label;
+                        break;
+                    }
+                }
+                if (!node.thedef) {
+                    var s = node.start;
+                    js_error("Undefined label " + node.name, s.file, s.line, s.col, s.pos);
+                }
+            }
+        }));
         return ast;
     };