Fix a number of tests that incorrectly used assertUnreachable.

test/mjsunit/regress/regress-244.js

Index: test/mjsunit/regress/regress-244.js
diff --git a/test/mjsunit/regress/regress-244.js b/test/mjsunit/regress/regress-244.js
index dc5336f846e42fb3894157869f4d379309c380e6..7503b1549f703ec886875bda6cccb064ba0dae1b 100644
--- a/test/mjsunit/regress/regress-244.js
+++ b/test/mjsunit/regress/regress-244.js
@@ -54,13 +54,14 @@ function run() {
   }
   for (var i = 0; i < kIllegalEncoded.length; i++) {
     var value = kIllegalEncoded[i];
-    var threw = false;
+    var exception = false;
     try {
       decodeURI(value);
-      assertUnreachable(value);
     } catch (e) {
+      exception = true;
       assertInstanceof(e, URIError);
     }
+    assertTrue(exception);
   }
 }