Fix a bug in dart2js's shrinking reductions.

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

Index: pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
diff --git a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart b/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
index 0e4d97ac02d759d00975e5613589589532b4280c..6ac916253bb82579b3f95b90b9fbcd844ce5f9b0 100644
--- a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
+++ b/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
@@ -278,9 +278,12 @@ bool _isBetaContLin(Continuation cont) {
 
   // Beta-reduction will move the continuation's body to its unique invocation
   // site.  This is not safe if the body is moved into an exception handler
-  // binding.
+  // binding.  Search from the invocation to the continuation binding to
+  // make sure that there is no binding for a handler.
   Node current = invoke.parent;
   while (current != cont.parent) {
+    // There is no need to reduce a beta-redex inside a deleted subterm.
+    if (current == ShrinkingReducer._DELETED) return false;
     if (current is LetHandler) return false;
     current = current.parent;
   }