Revert "dart2js: fix for https://github.com/dart-lang/sdk/issues/24412"

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

Index: pkg/compiler/lib/src/js_backend/codegen/codegen.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
index 791677068760e9f52c606fbbc7d3729894f60943..963f1d7f43ae700436985490c217268f38209910 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
@@ -639,14 +639,6 @@ class CodeGenerator extends tree_ir.StatementVisitor
 
   @override
   void visitTry(tree_ir.Try node) {
-    void register(ClassElement classElement) {
-      if (classElement == null) return;
-      registry.registerInstantiatedClass(classElement);
-    }
-    // We might catch JavaScript exceptions.
-    register(glue.jsPlainJavaScriptObjectClass);
-    register(glue.jsUnknownJavaScriptObjectClass);
-
     js.Block tryBlock = buildBodyBlock(node.tryBody);
     tree_ir.Variable exceptionVariable = node.catchParameters.first;
     js.VariableDeclaration exceptionParameter =