dart2js: permit generation of conditionals as arguments of allocations.

pkg/compiler/lib/src/ssa/codegen_helpers.dart

Index: pkg/compiler/lib/src/ssa/codegen_helpers.dart
diff --git a/pkg/compiler/lib/src/ssa/codegen_helpers.dart b/pkg/compiler/lib/src/ssa/codegen_helpers.dart
index 98db71e1a9dcbb2aa44d9222014e264e357ec4b0..531f3233a2eef8a2b005180af9204b490bf80a54 100644
--- a/pkg/compiler/lib/src/ssa/codegen_helpers.dart
+++ b/pkg/compiler/lib/src/ssa/codegen_helpers.dart
@@ -637,6 +637,9 @@ class SsaConditionMerger extends HGraphVisitor {
   }
 
   bool isSafeToGenerateAtUseSite(HInstruction user, HInstruction input) {
+    // HForeignNew evaluates arguments in order and passes them to a
+    // constructor.
+    if (user is HForeignNew) return true;
     // A [HForeign] instruction uses operators and if we generate
     // [input] at use site, the precedence might be wrong.
     if (user is HForeign) return false;