Use weak cells in map checks in polymorphic ICs.

test/mjsunit/opt-elements-kind.js

Index: test/mjsunit/opt-elements-kind.js
diff --git a/test/mjsunit/opt-elements-kind.js b/test/mjsunit/opt-elements-kind.js
index be7303b04bb1aea76242e7bab039471ce15fca8d..5f4f437299a5551d6c0075095630b5209bacb3f6 100644
--- a/test/mjsunit/opt-elements-kind.js
+++ b/test/mjsunit/opt-elements-kind.js
@@ -142,10 +142,16 @@ function test1() {
   assertTrue(%HaveSameMap(smis, doubles));
 }
 
+function clear_ic_state() {
+  %ClearFunctionTypeFeedback(construct_smis);
+  %ClearFunctionTypeFeedback(construct_doubles);
+  %ClearFunctionTypeFeedback(convert_mixed);
+}
+
 test1();
-gc(); // clear IC state
+clear_ic_state();
 test1();
-gc(); // clear IC state
+clear_ic_state();
 %OptimizeFunctionOnNextCall(test1);
 test1();
-gc(); // clear IC state
+clear_ic_state();