Handle malformed elements in onElementResolved.

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

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 5bd42a15262408b0890760448a291889624241d7..05b00d18ac7597b2ca7f308ba7d8f447340387ea 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -2425,6 +2425,12 @@ class JavaScriptBackend extends Backend {
   }
 
   void onElementResolved(Element element, TreeElements elements) {
+    if (element.isMalformed) {
+      // Elements that are marker as malformed during parsing or resolution
+      // might be registered here. These should just be ignored.
+      return;
+    }
+
     if ((element.isFunction || element.isConstructor) &&
         annotations.noInline(element)) {
       inlineCache.markAsNonInlinable(element);