dart2js cps: More aggressive operator specialization.

tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js

Index: tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js
diff --git a/tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js b/tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js
index 915d2371ceecd863ed9bcf21a46b4f14ce871b2b..52320ff3b41de12bf2c363cf5456929b6d1c93eb 100644
--- a/tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js
+++ b/tests/compiler/dart2js/cps_ir/expected/argument_refinement_20.js
@@ -10,12 +10,12 @@
 // }
 
 function() {
-  var x = P.int_parse("1233", null, null), y = P.int_parse("1234", null, null), v0 = typeof y === "number";
-  P.print(J.$div$n(x, 2));
+  var x = P.int_parse("1233", null, null), y = P.int_parse("1234", null, null);
+  P.print(x / 2);
   P.print(true);
-  P.print(v0);
-  if (!v0)
-    throw H.wrapException(H.argumentErrorValue(y));
+  P.print(typeof y === "number");
+  if (typeof y !== "number")
+    return H.iae(y);
   P.print(x * y);
   P.print(true);
 }