dart2js cps: Debugging utility and fix idempotency in shrinking reducer.

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

Index: pkg/compiler/lib/src/cps_ir/redundant_join.dart
diff --git a/pkg/compiler/lib/src/cps_ir/redundant_join.dart b/pkg/compiler/lib/src/cps_ir/redundant_join.dart
index 92f64ae252fbfff866cf0ac8cb4716d16dfd7d9e..808c1c73eed90f4720503ae95a60cc9b646866a0 100644
--- a/pkg/compiler/lib/src/cps_ir/redundant_join.dart
+++ b/pkg/compiler/lib/src/cps_ir/redundant_join.dart
@@ -8,15 +8,15 @@ import 'cps_ir_nodes.dart';
 import 'optimizers.dart';
 
 /// Eliminates redundant join points.
-/// 
+///
 /// A redundant join point is a continuation that immediately branches
 /// based on one of its parameters, and that parameter is a constant value
 /// at every invocation. Each invocation is redirected to jump directly
 /// to the branch target.
-/// 
+///
 /// Internally in this pass, parameters are treated as names with lexical
 /// scoping, and a given parameter "name" may be declared by more than
-/// one continuation. The reference chains for parameters are therefore 
+/// one continuation. The reference chains for parameters are therefore
 /// meaningless during this pass, until repaired by [AlphaRenamer] at
 /// the end.
 class RedundantJoinEliminator extends TrampolineRecursiveVisitor implements Pass {
@@ -113,11 +113,11 @@ class RedundantJoinEliminator extends TrampolineRecursiveVisitor implements Pass
       return;
     }
 
-    // Lift any continuations bound inside branchCont so they are in scope at 
+    // Lift any continuations bound inside branchCont so they are in scope at
     // the call sites. When lifting, the parameters of branchCont fall out of
     // scope, so they are added as parameters on each lifted continuation.
     // Schematically:
-    // 
+    //
     //   (LetCont (branchCont (x1, x2, x3) =
     //        (LetCont (innerCont (y) = ...) in
     //        [... innerCont(y') ...]))
@@ -127,8 +127,8 @@ class RedundantJoinEliminator extends TrampolineRecursiveVisitor implements Pass
     //   (LetCont (innerCont (y, x1, x2, x3) = ...) in
     //   (LetCont (branchCont (x1, x2, x3) =
     //        [... innerCont(y', x1, x2, x3) ...])
-    // 
-    // Parameter objects become shared between branchCont and the lifted 
+    //
+    // Parameter objects become shared between branchCont and the lifted
     // continuations. [AlphaRenamer] will clean up at the end of this pass.
     LetCont outerLetCont = branchCont.parent;
     while (branchCont.body is LetCont) {
@@ -202,13 +202,13 @@ class RedundantJoinEliminator extends TrampolineRecursiveVisitor implements Pass
 /// Ensures parameter objects are not shared between different continuations,
 /// akin to alpha-renaming variables so every variable is named uniquely.
 /// For example:
-/// 
+///
 ///   LetCont (k1 x = (return x)) in
 ///   LetCont (k2 x = (InvokeContinuation k3 x)) in ...
-///     => 
+///     =>
 ///   LetCont (k1 x = (return x)) in
 ///   LetCont (k2 x' = (InvokeContinuation k3 x')) in ...
-/// 
+///
 /// After lifting LetConts in the main pass above, parameter objects can have
 /// multiple bindings. Each reference implicitly refers to the binding that
 /// is currently in scope.