Add asserts to try to flush out test flakiness.

test/mjsunit/elements-kind.js

Index: test/mjsunit/elements-kind.js
diff --git a/test/mjsunit/elements-kind.js b/test/mjsunit/elements-kind.js
index c0bc333a6b92c3faff5f8e04f9fa2567b417bca7..4aa79de659836a2862f19e9f9be4066d15268d1f 100644
--- a/test/mjsunit/elements-kind.js
+++ b/test/mjsunit/elements-kind.js
@@ -147,6 +147,7 @@ assertKind(elements_kind.external_pixel,          new PixelArray(512));
 
 // Crankshaft support for smi-only array elements.
 function monomorphic(array) {
+  assertKind(elements_kind.fast_smi_only, array);
   for (var i = 0; i < 3; i++) {
     array[i] = i + 10;
   }
@@ -157,6 +158,7 @@ function monomorphic(array) {
   }
 }
 var smi_only = new Array(1, 2, 3);
+assertKind(elements_kind.fast_smi_only, smi_only);
 for (var i = 0; i < 3; i++) monomorphic(smi_only);
 %OptimizeFunctionOnNextCall(monomorphic);
 monomorphic(smi_only);