Fix TryICData to create ICData with a valid arguments decriptor.

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
===================================================================
--- runtime/vm/flow_graph_compiler_x64.cc	(revision 35593)
+++ runtime/vm/flow_graph_compiler_x64.cc	(working copy)
@@ -1274,6 +1274,7 @@
     intptr_t deopt_id,
     intptr_t token_pos,
     LocationSummary* locs) {
+  ASSERT(Array::Handle(ic_data.arguments_descriptor()).Length() > 0);
   // Each ICData propagated from unoptimized to optimized code contains the
   // function that corresponds to the Dart function of that IC call. Due
   // to inlining in optimized code, that function may not correspond to the
@@ -1297,6 +1298,7 @@
                                          intptr_t deopt_id,
                                          intptr_t token_pos,
                                          LocationSummary* locs) {
+  ASSERT(Array::Handle(ic_data.arguments_descriptor()).Length() > 0);
   __ LoadObject(RBX, ic_data, PP);
   GenerateDartCall(deopt_id,
                    token_pos,
@@ -1317,7 +1319,7 @@
   const String& name = String::Handle(ic_data.target_name());
   const Array& arguments_descriptor =
       Array::ZoneHandle(ic_data.arguments_descriptor());
-  ASSERT(!arguments_descriptor.IsNull());
+  ASSERT(!arguments_descriptor.IsNull() && (arguments_descriptor.Length() > 0));
   const MegamorphicCache& cache =
       MegamorphicCache::ZoneHandle(table->Lookup(name, arguments_descriptor));
   Label not_smi, load_cache;