Overhaul tree IR visitor and rename IR classes.

pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart
index 0b115cbd533363f596fefefd3171c8cffa882442..e7a7d14284d2dbcf6d1829ace3bfaafa4c9c2085 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_integrity.dart
@@ -26,7 +26,7 @@ const bool ENABLE_DUMP = tracer.TRACE_FILTER_PATTERN != null;
 ///
 class CheckCpsIntegrity extends RecursiveVisitor {
 
-  ExecutableDefinition topLevelNode;
+  RootNode topLevelNode;
 
   Set<Definition> seenDefinitions = new Set<Definition>();
   Map<Definition, Set<Reference>> seenReferences =
@@ -78,7 +78,7 @@ class CheckCpsIntegrity extends RecursiveVisitor {
   }
 
   @override
-  visitRunnableBody(RunnableBody node) {
+  visitBody(Body node) {
     markAsSeen(node.returnContinuation);
     if (!node.returnContinuation.isReturnContinuation) {
       error('Return continuation with a body', node);
@@ -209,7 +209,7 @@ class CheckCpsIntegrity extends RecursiveVisitor {
           '$sexpr\n';
   }
 
-  void check(ExecutableDefinition node) {
+  void check(RootNode node) {
     topLevelNode = node;
     visit(node);