Revert "Fix misoptimization of 'is' test"

tests/standalone/regress_29695_test.dart

Index: tests/standalone/regress_29695_test.dart
diff --git a/tests/standalone/regress_29695_test.dart b/tests/standalone/regress_29695_test.dart
index 78c9dcef0272f6535a395d8ee993c1d19ca8b43d..73641a50d841a23630c95b308349811da25bcf03 100644
--- a/tests/standalone/regress_29695_test.dart
+++ b/tests/standalone/regress_29695_test.dart
@@ -12,6 +12,7 @@ main() {
 
 // Prime the IC with things that are and are not ints.
 void train() {
+  int sum = 0;
   for (int i = 0; i < 10000; i++) {
     IsAnInt(42); // Smi - always goes first in the generated code.
     IsAnInt(1 << 62); // Mint on 64 bit platforms.
@@ -24,4 +25,4 @@ void train() {
   }
 }
 
-bool IsAnInt(f) => f is int;
+int IsAnInt(Foo f) => f is int;