Ensure only a subset of elements enter in Compiler.analyzedElement.

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/compiler.dart	(revision 27842)
+++ sdk/lib/_internal/compiler/implementation/compiler.dart	(working copy)
@@ -1193,6 +1193,14 @@
   }
 
   TreeElements analyzeElement(Element element) {
+    assert(invariant(element,
+           element.impliesType() ||
+           element.isField() ||
+           element.isFunction() ||
+           element.isGenerativeConstructor() ||
+           element.isGetter() ||
+           element.isSetter(),
+           message: 'Unexpected element kind: ${element.kind}'));
     assert(invariant(element, element.isDeclaration));
     ResolutionEnqueuer world = enqueuer.resolution;
     TreeElements elements = world.getCachedElements(element);