dart2js cps: Retain refinement nodes and update refinements after GVN.

pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart

Index: pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart
diff --git a/pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart b/pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart
index 599989ac78ccbe70329918fa9ee5af82f4d48c47..1e9d702b2fde03c69223f085621ae93657bc168c 100644
--- a/pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart
+++ b/pkg/compiler/lib/src/cps_ir/optimize_interceptors.dart
@@ -123,6 +123,7 @@ class OptimizeInterceptors extends TrampolineRecursiveVisitor implements Pass {
           sourceInformation: interceptor.sourceInformation);
       CpsFragment cps = new CpsFragment(interceptor.sourceInformation);
       Parameter param = new Parameter(interceptor.hint);
+      param.type = interceptor.type;
       Continuation cont = cps.letCont(<Parameter>[param]);
       if (interceptor.interceptedClasses.every(hasNoFalsyValues)) {
         // If null is the only falsy value, compile as "x && CONST".