Handle malformed elements in onElementResolved.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 2407 matching lines @@
   void onQueueClosed() {
     lookupMapAnalysis.onQueueClosed();
     jsInteropAnalysis.onQueueClosed();
   }
 
   void onCodegenStart() {
     lookupMapAnalysis.onCodegenStart();
   }
 
   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);
     }
 
     LibraryElement library = element.library;
     if (!library.isPlatformLibrary && !canLibraryUseNative(library)) return;
     bool hasNoInline = false;
     bool hasForceInline = false;
     bool hasNoThrows = false;
@@ skipping 720 matching lines @@
     }
   }
 
   @override
   void onImpactUsed(ImpactUseCase impactUse) {
     if (impactUse == DeferredLoadTask.IMPACT_USE) {
       resolution.emptyCache();
     }
   }
 }