Collect is checks to only emit the ones that are needed.

frog/leg/compiler.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.
 
 class WorkItem {
   final Element element;
   TreeElements resolutionTree;
   Function run;
   Map<int, BailoutInfo> bailouts = null;
   bool allowSpeculativeOptimization = true;
@@ skipping 343 matching lines @@
   }
 
   void registerDynamicSetter(SourceString methodName) {
     universe.invokedSetters.add(methodName);
   }
 
   void registerInstantiatedClass(ClassElement element) {
     universe.instantiatedClasses.add(element);
   }
 
+  // TODO(ngeoffray): This should get a type.
+  void registerIsCheck(Element element) {
+    universe.isChecks.add(element);
+  }
+
   Type resolveType(ClassElement element) {
     return withCurrentElement(element, () => resolver.resolveType(element));
   }
 
   FunctionParameters resolveSignature(FunctionElement element) {
     return withCurrentElement(element,
                               () => resolver.resolveSignature(element));
   }
 
   Object compileVariable(VariableElement element) {
@@ skipping 117 matching lines @@
   }
 }
 
 class SourceSpan {
   final Uri uri;
   final int begin;
   final int end;
 
   const SourceSpan(this.uri, this.begin, this.end);
 }