Fix bug in SsaConstructionFieldTypes where the phase got confused seeing multiple HForeignNew due t…

sdk/lib/_internal/compiler/implementation/ssa/optimize.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/optimize.dart	(revision 23325)
+++ sdk/lib/_internal/compiler/implementation/ssa/optimize.dart	(working copy)
@@ -1437,6 +1437,11 @@
   }
 
   visitForeignNew(HForeignNew node) {
+    if (!work.element.isGenerativeConstructor()) return;
+    // Check if this is the new object allocated by this generative
+    // constructor. Inlining might add other [HForeignNew]
+    // instructions in the graph.
+    if (!node.usedBy.any((user) => user is HReturn)) return;
     // The HForeignNew instruction is used in the generative constructor to
     // initialize all fields in newly created objects. The fields are
     // initialized to the value present in the initializer list or set to null