Create new interface instead of ClosureClassMap for variable usage information that is not Element-…

pkg/compiler/lib/src/dump_info.dart

Index: pkg/compiler/lib/src/dump_info.dart
diff --git a/pkg/compiler/lib/src/dump_info.dart b/pkg/compiler/lib/src/dump_info.dart
index fcecf0c44d08cf56cf4a2e240b71399ec571e45c..e8e31f8448b78870a0ee7890fc7488ddff2a6bb5 100644
--- a/pkg/compiler/lib/src/dump_info.dart
+++ b/pkg/compiler/lib/src/dump_info.dart
@@ -214,11 +214,8 @@ class ElementInfoCollector extends BaseElementVisitor<Info, dynamic> {
         size: compiler.dumpInfoTask.sizeOf(element));
     _elementToInfo[element] = closureInfo;
 
-    ClosureClassMap closureMap = compiler.closureToClassMapper
-        .getClosureToClassMapping(element.methodElement);
-    assert(closureMap != null && closureMap.closureClassElement == element);
-
-    FunctionInfo functionInfo = this.process(closureMap.callElement);
+    FunctionInfo functionInfo = this.process(
+        compiler.closureToClassMapper.getCallEntity(element.methodElement));
     if (functionInfo == null) return null;
     closureInfo.function = functionInfo;
     functionInfo.parent = closureInfo;