dart2js cps: Stack trace should be obtained from raw exception value.

pkg/compiler/lib/src/js_backend/codegen/unsugar.dart

Index: pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart b/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
index fab6a450bd7a00728e921932bd3ce70a3071258a..e0115f21c2e7102fb63b8c43a8f21d86937352c8 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
@@ -193,7 +193,7 @@ class UnsugarVisitor extends RecursiveVisitor {
       if (stackTraceParameter.hasAtLeastOneUse) {
         Parameter stackTraceValue = new Parameter(null);
         stackTraceValue.substituteFor(stackTraceParameter);
-        insertStaticCall(_glue.getTraceFromException(), [exceptionValue],
+        insertStaticCall(_glue.getTraceFromException(), [_exceptionParameter],
             stackTraceValue, body);
       }
     }