Add ScopeInfo class for variable information that doesn't actually involve closures.

tests/compiler/dart2js/closure/closure_test.dart

Index: tests/compiler/dart2js/closure/closure_test.dart
diff --git a/tests/compiler/dart2js/closure/closure_test.dart b/tests/compiler/dart2js/closure/closure_test.dart
index 8db19bd1915d59c5dc17b814634bc902a93667df..d348cd28ac3a864e79d673bcb6399f97634ea4f7 100644
--- a/tests/compiler/dart2js/closure/closure_test.dart
+++ b/tests/compiler/dart2js/closure/closure_test.dart
@@ -128,7 +128,7 @@ class ClosureIrChecker extends AbstractIrComputer {
 /// Compute a string representation of the data stored for [local] in [info].
 String computeLocalValue(ClosureRepresentationInfo info, Local local) {
   StringBuffer sb = new StringBuffer();
-  if (info.variableIsUsedInTryOrSync(local)) {
+  if (info.variablesUsedInTryOrSync.contains(local)) {
     sb.write('inTry');
   }
   // TODO(johnniwinther,efortuna): Add more info (captured, boxed etc.).